Combustion burner, solid-fuel-combustion burner, solid-fuel-combustion boiler, boiler, and method for operating boiler

ABSTRACT

Provided is a combustion burner including: a fuel nozzle ( 51 ) that is able to blow a fuel gas obtained by mixing pulverized coal with primary air; a secondary air nozzle ( 52 ) that is able to blow secondary air from the outside of the fuel nozzle ( 51 ); a flame stabilizer ( 54 ) that is provided at a front end portion of the fuel nozzle ( 51 ) so as to be near the axis center; and a rectification member ( 55 ) that is provided between the inner wall surface of the fuel nozzle ( 51 ) and the flame stabilizer ( 54 ), wherein an appropriate flow of a fuel gas obtained by mixing solid fuel with air may be realized.

CROSS-REFERENCE TO RELATED APPLICATIONS

This is a divisional of U.S. patent application Ser. No. 14/007,858,filed on Sep. 26, 2013, of which is a 371 of PCT/JP2012/055850 filedMar. 7, 2012, of which claims foreign priority over Japanese ApplicationNo. 2011-081876 filed Apr. 1, 2011, Japanese Application No. 2011-081877filed Apr. 1, 2011, Japanese Application No. 2011-081879 filed Apr. 1,2011, Japanese Application No. 2011-138563 filed Jun. 22, 2011, andJapanese Application No. 2011-138564 filed Jun. 22, 2011, the entirecontents of which is incorporated herein by reference.

FIELD

The present invention relates to a combustion burner that is applied toa boiler for producing steam to be used to generate electric power or tobe used in a factory or the like. For example, the combustion burner isa solid-fuel-combustion burner that burns solid fuel (pulverized fuel)such as pulverized coal. Also, the invention relates to asolid-fuel-combustion boiler, a boiler that produces steam by burningsolid fuel and air, and a method for operating the boiler.

BACKGROUND

For example, a conventional pulverized-coal-combustion boiler includes afurnace which is formed in a hollow shape and is provided in thevertical direction, and plural combustion burners are disposed in afurnace wall in the circumferential direction and are disposed at pluralstages in the up and down direction. A fuel-air mixture obtained bymixing primary air with pulverized coal (fuel) formed by milling coal issupplied to the combustion burners, and hot secondary air is supplied tothe combustion furnaces so that the fuel-air mixture and the secondaryair blow into the furnace. Accordingly, a flame is generated, and hencethe fuel-air mixture may be burned inside the furnace by the flame.Then, a flue gas duct is connected to the upper portion of the furnace,and the flue gas duct is equipped with a superheater, a repeater, aneconomizer, and the like for collecting the heat of a flue gas. Thus,steam may be produced by the heat exchange between water and the fluegas produced by the combustion in the furnace.

As such a pulverized-coal-combustion boiler or such a combustion burner,for example, pulverized-coal-combustion boilers or combustion burnersdisclosed in Patent Literatures below are known.

CITATION LIST Patent Literature

Patent Literature 1: Japanese Laid-open Patent Publication No. 08-135919

Patent Literature 2: Japanese Laid-open Patent Publication No.2006-189188

Patent Literature 3: Japanese Laid-open Patent Publication No. 8-296815

Patent Literature 4: Japanese Laid-open Patent Publication No. 9-203505

Patent Literature 5: Japanese Laid-open Patent Publication No.2006-057903

Patent Literature 6: Japanese Laid-open Patent Publication No.2008-145007

SUMMARY Technical Problem

In the above-described conventional combustion burner, when a fuel gasobtained by mixing pulverized coal with air collides with a flamestabilizer, a separation of a flow occurs at a rear end portion of theflame stabilizer, and hence it is difficult to sufficiently exhibit theflame stabilization ability at the front end portion of the flamestabilizer. Further, in the conventional boiler, since the pulverizedcoal contains moisture or a volatile content, operation parameters needto be adjusted based on the operation output of the boiler. In thiscase, it is difficult to directly set the operation parameters from thecharacteristics of the coal.

It is an object of the invention to provide a combustion burner, asolid-fuel-combustion burner, and a solid-fuel-combustion boiler capableof realizing an appropriate flow of a fuel gas obtained by mixing solidfuel with air.

Further, it is another object of the invention to provide a boiler and amethod for operating the boiler capable of improving operationefficiency by appropriately burning solid fuel and a volatile contentcontained in the solid fuel.

Solution to Problem

According to an aspect of the present invention, a combustion burnerincludes: a fuel nozzle that is able to blow a fuel gas obtained bymixing solid fuel with air; a secondary air nozzle that is able to blowair from the outside of the fuel nozzle; a flame stabilizer that isprovided at a front end portion of the fuel nozzle so as to be near anaxis center side of the fuel nozzle; and a rectification member that isprovided between an inner wall surface of the fuel nozzle and the flamestabilizer.

Accordingly, since a rectification member is provided between the innerwall surface of the fuel nozzle and the flame stabilizer, the flow ofthe fuel gas flowing through the fuel nozzle is rectified by therectification member, and the separation of the flow at the rear endportion of the flame stabilizer is suppressed. Also, since the flowvelocity becomes substantially uniform, the deposit of the solid fuel tothe wall surface of the fuel nozzle is suppressed. Thus, the appropriateflow of the fuel gas may be realized.

Advantageously, in the combustion burner, the rectification member isdisposed so as to have a predetermined gap with respect to the flamestabilizer.

Accordingly, since a predetermined gap is ensured between therectification member and the flame stabilizer, the flow of the fuel gasflowing between the rectification member and the flame stabilizer isrectified, and hence the flame stabilizing function using the flamestabilizer may be sufficiently exhibited.

Advantageously, in the combustion burner, the rectification member isprovided so that a distance between the rectification member and theflame stabilizer is substantially uniform in the fuel gas flowingdirection.

Accordingly, since the distance between the rectification member and theflame stabilizer is substantially equal in the fuel gas flowingdirection by the rectification member, the flow velocity of the fuel gasflowing between the rectification member and the flame stabilizerbecomes substantially uniform, and hence the deposit of the solid fuelto the fuel nozzle or the attachment of the solid fuel to the flamestabilizer may be suppressed. Further, since the passage is notextremely narrowed, the blockage of the passage may be prevented.

Advantageously, in the combustion burner, a widened portion is providedat the downstream side of the flame stabilizer in the fuel gas flowingdirection and a tapered portion is provided at the downstream side ofthe rectification member in the fuel gas flowing direction.

Accordingly, since the front end portion of the flame stabilizer isequipped with the widened portion, the flame may be reliably realized.Then, since the front end portion of the rectification member isequipped with the tapered portion, the distance between the flamestabilizer and the rectification member becomes substantially uniform inthe fuel gas flowing direction.

Advantageously, in the combustion burner, a widened portion is providedat the downstream side of the flame stabilizer in the fuel gas flowingdirection, and the rectification member is provided at a position wherethe rectification member does not face the widened portion.

Accordingly, since the rectification member is provided at a positionwhere the rectification member does not face the widened portion of theflame stabilizer, the fuel gas passage between the widened portion ofthe flame stabilizer and the fuel nozzle is not narrowed, and the flowvelocity of the fuel gas becomes substantially uniform. Accordingly, itis possible to suppress the deposit of the solid fuel to the fuel nozzleor the attachment of the solid fuel to the flame stabilizer.

Advantageously, in the combustion burner, the rectification member isprovided along the inner wall surface of the fuel nozzle.

Accordingly, since the rectification member is provided in the innerwall surface of the fuel nozzle, a separate attachment member or thelike is not needed. Thus, the assembling workability may be improved andthe manufacturing cost may be reduced.

Advantageously, in the combustion burner, the flame stabilizer is formedin a structure in which a first flame stabilizing member disposed in thehorizontal direction and a second flame stabilizing member disposed inthe vertical direction are disposed so as to intersect each other.

Accordingly, since the flame stabilizer is formed in a structure inwhich the first flame stabilizing member intersects the second flamestabilizing member, the sufficient flame stabilizing function may beensured.

Advantageously, in the combustion burner, the first flame stabilizingmember and the second flame stabilizing member respectively include aplurality of flame stabilizing members, a plurality of the first flamestabilizing members are disposed in the vertical direction with apredetermined gap therebetween, a plurality of the second flamestabilizing members are disposed in the horizontal direction with apredetermined gap therebetween, and the plurality of first flamestabilizing members and the plurality of second flame stabilizingmembers are disposed so as to intersect each other.

Accordingly, since the flame stabilizer is formed in a double crossstructure, the sufficient flame stabilizing function may be ensured.

Advantageously, in the combustion burner, in any one of the first flamestabilizing member and the second flame stabilizing member, one sidewidth is set to be larger than the other side width.

Accordingly, when the width of the first flame stabilizing memberdisposed in the horizontal direction increases, the flame stabilizingfunction in the horizontal direction may be improved by the first flamestabilizing member with a wide width. Further, when the width of thesecond flame stabilizing member disposed in the vertical directionincreases, the flame stabilizing function may be improved without theadverse influence of the second flame stabilizing member when thedirection of the nozzle swings up and down for the steam temperaturecontrol or the like. This is because of the following reasons. When thenozzle moves up and down, the position of the flame stabilizing memberwith respect to the fuel gas blowing position largely changes in thefirst flame stabilizing member, but substantially does not change in thesecond flame stabilizing member.

According to another aspect of the present invention, a combustionburner includes: a fuel nozzle that is able to blow a fuel gas obtainedby mixing solid fuel with air; a secondary air nozzle that is able toblow air from the outside of the fuel nozzle; a flame stabilizer that isprovided at a front end portion of the fuel nozzle so as to be near anaxis center side of the fuel nozzle; and a guide member that guides thefuel gas flowing through the fuel nozzle toward the axis center side ofthe fuel nozzle.

Accordingly, since the guide member is provided so as to guide the fuelgas flowing through the fuel nozzle toward the axis center side of thefuel nozzle, the fuel gas flowing through the fuel nozzle is guided bythe guide member toward the axis center side of the fuel nozzle, andhence the appropriate flow of the fuel gas may be realized. As a result,the inner flame stabilization performance may be improved, and hence theNOx production amount may be reduced.

Advantageously, in the combustion burner, the guide member guides thefuel gas in a direction in which the fuel gas is separated from thesecondary air blown from the secondary air nozzle.

Accordingly, the fuel gas is guided by the guide member in a directionin which the fuel gas is separated from the secondary air and the mixingof the fuel gas and the secondary air is suppressed, and hence the outerperipheral portion of the combustion flame is maintained at a lowtemperature. For this reason, the NOx production amount caused by themixing of the combustion gas and the secondary air may be reduced.

Advantageously, in the combustion burner, the guide member is disposedalong an inner wall surface of the fuel nozzle.

Accordingly, since the guide member is disposed in the inner wallsurface of the fuel nozzle, the fuel gas flowing through the fuel nozzleis effectively guided toward the axis center side of the fuel nozzle,and hence the fuel gas may be guided in a direction in which the fuelgas is separated from the secondary air.

Advantageously, in the combustion burner, the guide member is disposedat the front end portion of the fuel nozzle so as to face the flamestabilizer.

Accordingly, since the guide member is disposed so as to face the flamestabilizer, the inner flame stabilization performance may be improved.

Advantageously, in the combustion burner, the guide member is disposedat a position where the guide member faces the inner wall surface of thefuel nozzle in the flame stabilizer.

Accordingly, the fuel gas flowing along the flame stabilizer may beeffectively guided by the guide member toward the front end portion ofthe flame stabilizer so as to stabilize the flame.

Advantageously, in the combustion burner, the guide member is disposedat the upstream side of the flame stabilizer in the fuel gas flowingdirection.

Accordingly, since the guide member is separated from the flamestabilizer, the guide member does not degrade the flame stabilizingfunction of the flame stabilizer.

Advantageously, in the combustion burner, the flame stabilizer is formedin a structure in which two first flame stabilizing members provided inthe horizontal direction while being parallel to each other in thevertical direction with a predetermined gap therebetween and two secondflame stabilizing members provided in the vertical direction while beingparallel to each other in the horizontal direction with a predeterminedgap therebetween are disposed so as to intersect one another, and theguide member is disposed at the outside of the intersection position ofthe first flame stabilizing members and the second flame stabilizingmembers.

Accordingly, since the flame stabilizer is formed in a double crossstructure, the sufficient flame stabilizing function may be ensured, andthe fuel gas flowing through the fuel nozzle may be effectively guidedby the guide member toward the axis center side of the fuel nozzle.

Advantageously, in the combustion burner, the flame stabilizer includesa widened portion formed at the downstream side in the fuel gas flowingdirection, and the guide member is disposed so as to face the widenedportion.

Accordingly, the sufficient flame stabilizing function may be ensured.

Advantageously, in the combustion burner, the guide member includes twoflame stabilizing members that are provided in the horizontal directionwhile being parallel to each other in the vertical direction with apredetermined gap therebetween, and the guide member is provided so thatthe front end portions of the flame stabilizing members face the axiscenter side of the fuel nozzle.

Accordingly, since the guide member is formed by the flame stabilizingmember, the structure may be simplified.

According to still another aspect of the present invention, asolid-fuel-combustion burner that is used in the burner portion of asolid-fuel-combustion boiler and inputs pulverized solid fuel and airinto a furnace, includes: a fuel burner that inputs pulverized fuel andprimary air into the furnace; and a secondary air input port that ejectssecondary air from the outer periphery of the fuel burner. A cross typesplit member obtained by intersecting a plurality of inner flamestabilization members in a plurality of directions is disposed at afront side of a passage of the fuel burner, and the width of the splitmember is different for each direction.

According to such a solid-fuel-combustion burner, thesolid-fuel-combustion burner includes the fuel burner that inputs thepulverized fuel and the primary air into the furnace and the secondaryair input port that ejects the secondary air from the outer periphery ofthe fuel burner, the cross type split member obtained by intersectingthe plurality of inner flame stabilization members in a plurality ofdirections is disposed at the front side of the passage of the fuelburner, and the width of the split member is different for eachdirection. For this reason, since the split member provided near thecenter of the outlet opening divides the passage of the pulverized coaland the air so as to disturb the flow therein, and forms a recirculationzone at the front side of the split member, the split member serves asan inner flame stabilization mechanism. As a result, it is possible tosuppress the hot oxygen remaining zone formed in the outer periphery ofthe flame.

In the above-described invention, the cross type split member may bewide in the up and down direction. Thus, even when the nozzle anglechanges in the up and down direction, the positional relation withrespect to the splitter member hardly changes.

In the above-described invention, the cross type split member may bewide in the left and right direction. Thus, since the splitter functionin the horizontal direction is strengthened, the direct interferencewith the secondary air input from the up and down direction may besuppressed.

In the above-described invention, three or more cross type split membersare disposed in at least one of the left and right direction and the upand down direction. Furthermore, the center portions in at least one ofthe left and right direction and the up and down direction may be wide.Thus, the inner ignition may be strengthened while preventing the outerperipheral ignition.

According to still another aspect of the present invention, asolid-fuel-combustion burner that is used in the burner portion of asolid-fuel-combustion boiler, includes a fuel burner with an inner flamestabilization function and a secondary air input port without a flamestabilization function, and inputs pulverized solid fuel and air into afurnace, includes: the fuel burner that inputs pulverized fuel andprimary air into a furnace; and the secondary air input port that ejectssecondary air from the outer periphery of the fuel burner. A cross typesplit member obtained by intersecting a plurality of members in aplurality of directions is disposed at a front side of a passage of thefuel burner, and a shielding member that reduces a passage sectionalarea is provided in at least one position of the intersecting cornersformed by the intersection of the split members.

According to such a solid-fuel-combustion burner, thesolid-fuel-combustion burner includes the fuel burner that inputs thepulverized fuel and the primary air into the furnace and the secondaryair input port that ejects the secondary air from the outer periphery ofthe fuel burner, the cross type split member obtained by intersectingthe plurality of members in a plurality of directions is disposed at thefront side of the passage of the fuel burner, and the shielding memberthat reduces the passage sectional area is provided in at least oneposition of the intersection corner formed by the intersection of thesplit members. For this reason, the inner flame stabilizing functionusing the cross type split member may be further strengthened.

In the above-described invention, the solid-fuel-combustion boiler maybe divided into the burner portion and the additional air input unit soas to perform the low NOx combustion. Thus, the reduction may be furtherstrongly performed by the division of the additional input air.

Advantageously, in the solid-fuel-combustion boiler, thesolid-fuel-combustion burner that inputs the pulverized fuel and the airinto the furnace is disposed at a corner or a wall surface inside thefurnace.

According to the solid-fuel-combustion boiler, since thesolid-fuel-combustion burner that inputs the pulverized fuel and the airinto the furnace is disposed at the corner or the wall surface insidethe furnace, the split member that is disposed near the center of theoutlet opening of the fuel burner and serves as the inner flamestabilization mechanism divides the passage of the pulverized fuel andthe air so as to disturb the flow. As a result, the mixture and thedispersion of the air are promoted to the inside of the flame, and hencethe ignition surface is further finely divided. Accordingly, since theignition position is near the center of the flame, the unburnedcombustible content of the fuel is reduced. That is, since oxygen easilyenters the center portion of the flame, the inner ignition iseffectively performed, and the reduction inside the flame promptlyoccurs. Thus, the NOx production amount is reduced.

According to another aspect of the present invention, asolid-fuel-combustion burner that is used in the burner portion of asolid-fuel-combustion boiler and inputs pulverized solid fuel and airinto a furnace, includes: a fuel burner that inputs pulverized fuel andprimary air into the furnace; and a coal secondary port that ejectssecondary air from the outer periphery of the fuel burner. A splitmember as an inner flame stabilization member is disposed at a frontside of a passage of the fuel burner, and a part of an end portionadjacent to the coal secondary port at the outer periphery of the splitmember is removed.

According to such a solid-fuel-combustion burner, thesolid-fuel-combustion burner includes the fuel burner that inputs thepulverized fuel and the primary air into the furnace and the coalsecondary port that ejects the secondary air from the outer periphery ofthe fuel burner, the split member as the inner flame stabilizationmember is disposed at the front side of the passage of the fuel burner,and a part of the end portion adjacent to the coal secondary port at theouter periphery of the split member is removed. For this reason, thesplit member that is provided near the center of the outlet openingdivides the passage of the pulverized coal and the air so as to disturbthe flow therein. Further, since the split member forms a recirculationzone at the front side of the split member, the split member serves asthe inner flame stabilization mechanism. As a result, the hot oxygenremaining zone formed at the outer periphery of the flame may besuppressed.

Particularly, in a zone in which the end portion of the split member isremoved, the ignition performed using the split member as the ignitionsource may be suppressed. Furthermore, the flame stabilizing function atthe center portion side of the split member as the inside of the flamemay be effectively used.

Advantageously, in the solid-fuel-combustion burner, the inner flamestabilization member is a cross type split member obtained byintersecting a plurality of members in a plurality of directions.

Advantageously, in the solid-fuel-combustion burner, a plurality ofsplit members of the inner flame stabilization member are disposed in atleast one direction.

In the above-described invention, the end portion of the cross typesplit member in any one direction of a plurality of directions may beremoved. Thus, the inner ignition may be promoted by reducing theignition source at the end portion of the split member. That is, in thecross type split member obtained by the intersection of two directionsof the up and down direction and the left and right direction, any oneof the end portions in the up and down direction and the left and rightdirection may be removed.

Particularly, in a case of a turning combustion type, the end potion ofthe split member in the up and down direction may be removed. Thus, itis possible to prevent a zone with a high temperature and a high oxygenconcentration from being formed at the upper and lower ends that mayeasily and directly interfere with the secondary air.

In the above-described invention, three or more cross type split membersmay be disposed in at least one of the up and down direction and theleft and right direction, and the end portions of the cross type splitmembers may be removed except for at least one cross type split memberdisposed at the center portion in at least one of the up and downdirection and the left and right direction. Thus, a structure isobtained in which the split member does not exist in a zone that issupposed to contribute the outer peripheral ignition the most.

In the above-described invention, the solid-fuel-combustion boiler maybe divided into the burner and the additional air input unit so as toperform the low NOx combustion. Thus, the reduction may be furtherstrongly performed by the division of the additional input air.

Advantageously, in the solid-fuel-combustion burner, thesolid-fuel-combustion burner that inputs the pulverized fuel and the airinto the furnace is disposed at a corner or a wall surface inside thefurnace.

According to such a solid-fuel-combustion boiler, since thesolid-fuel-combustion burner that inputs the pulverized fuel and the airinto the furnace is disposed in the corner or the wall surface insidethe furnace, the split member disposed near the center of the outletopening of the fuel burner and serving as the inner flame stabilizationmechanism divides the passage of the pulverized fuel and the air so asto disturb the flow thereof. As a result, the mixture and the dispersionof the air are promoted to the inside of the flame, and hence theignition surface is further finely divided.

Accordingly, since the ignition position is near the center of theflame, the unburned combustible content of the fuel is reduced. That is,since oxygen easily enters the center portion of the flame, the innerignition is effectively performed, and the reduction inside the flame ispromptly occurs. Thus, the NOx production amount is reduced.

Particularly, in a zone in which the end portion of the split member isremoved, the ignition performed using the split member as the ignitionsource may be suppressed. Furthermore, the flame stabilizing function atthe center portion side of the split member as the inside of the flamemay be effectively used.

According to still another aspect of the present invention, a boilerincludes: a furnace that burns solid fuel and air; a heat exchanger thatcollects heat by a heat exchange inside the furnace; a fuel nozzle thatis able to blow a fuel gas obtained by mixing solid fuel with primaryair into the furnace; a secondary air nozzle that is able to blowsecondary air from the outside of the fuel nozzle to the furnace; anadditional air nozzle that is able to blow additional air to the upsideof the fuel nozzle and the secondary air nozzle in the furnace; an airamount adjusting device that is able to adjust the amount of the airsupplied to the fuel nozzle, the secondary air nozzle, and theadditional air nozzle; and a control device that controls the air amountadjusting device in response to a volatile content of the solid fuel.

Accordingly, since the control device controls the air amount adjustingdevice in response to the volatile content of the solid fuel so that theair amount adjusting device adjusts the amount of the air supplied tothe fuel nozzle, the secondary air nozzle, and the additional airnozzle, the primary air amount, the secondary air amount, and theadditional air amount are adjusted in response to the volatile contentof the solid fuel. Accordingly, the volatile content of the solid fuelmay be appropriately burned and the solid fuel may be appropriatelyburned. Thus, the production of the NOx or the unburned combustiblecontent is suppressed, and hence the boiler operation efficiency may beimproved.

Advantageously, in the boiler, the control device controls the airamount adjusting device in response to the volatile content of the solidfuel so as to adjust a distribution of the total air amount of theprimary air and the secondary air and the air amount of the additionalair.

Accordingly, the total air amount of the primary air and the secondaryair is the air amount necessary for burning the volatile content of thesolid fuel, and the total air amount of the primary air and thesecondary air changes in response to the volatile content of the solidfuel. Thus, the volatile content of the solid fuel may be appropriatelyburned.

Advantageously, in the boiler, the furnace is equipped with a tertiaryair nozzle that is able to blow tertiary air from the outside of thesecondary air nozzle, and the control device controls the air amountadjusting device in response to the volatile content of the solid fuelso as to adjust a distribution of the total air amount of the primaryair and the secondary air and the total air amount of the tertiary airand the additional air.

Accordingly, since the total air amount of the primary air and thesecondary air changes, the volatile content of the solid fuel may beappropriately burned.

Advantageously, in the boiler, the control device controls the airamount adjusting device so that the primary air amount and theadditional air amount become a predetermined air amount, and adjusts adistribution of the secondary air and the tertiary air in response tothe volatile content of the solid fuel.

Accordingly, since the primary air is the transportation air fortransporting the solid fuel and the additional air completely burns thesolid fuel so as to suppress the production of NOx, the primary air andthe additional air are set as the predetermined air amounts, and thedistribution of the secondary air and the tertiary air is adjusted inresponse to the volatile content of the solid fuel. Thus, the solid fueland the volatile content thereof may be appropriately burned whilemaintaining a predetermined fuel-air ratio.

Advantageously, in the boiler, the control device increases adistribution of the secondary air when the volatile content of the solidfuel increases.

Accordingly, since the secondary air is the combustion air mixed withthe fuel gas so as to burn the solid fuel, the solid fuel and thevolatile content thereof may be appropriately burned by increasing thedistribution of the secondary air when the volatile content of the solidfuel increases.

According to still another aspect of the present invention, a method foroperating a boiler including a furnace that burns solid fuel and air, aheat exchanger that collects heat by a heat exchange inside the furnace,a fuel nozzle that is able to blow a fuel gas obtained by mixing solidfuel with primary air to the furnace, a secondary air nozzle that isable to blow secondary air from the outside of the fuel nozzle into thefurnace, and an additional air nozzle that is able to blow additionalair to the upside of the fuel nozzle and the secondary air nozzle in thefurnace. A distribution of the secondary air and the tertiary air isadjusted in response to a volatile content of the solid fuel.

Accordingly, since the distribution of the secondary air and thetertiary air is adjusted in response to the volatile content of thesolid fuel, the volatile content of the solid fuel may be appropriatelyburned and the solid fuel may be appropriately burned. Thus, theproduction of the NOx or the unburned combustible content is suppressed,and hence the boiler operation efficiency may be improved.

Advantageously, in the method for operating the boiler, the distributionof the secondary air increases when the volatile content of the solidfuel increases.

Accordingly, since the secondary air is the combustion air mixed withthe fuel gas so as to burn the solid fuel, the solid fuel and thevolatile content thereof may be appropriately burned by increasing thedistribution of the secondary air when the volatile content of the solidfuel increases.

Advantageous Effects of Invention

According to the combustion burner of the invention, since thecombustion burner includes: the fuel nozzle that is able to blow thefuel gas obtained by mixing the solid fuel and the air; the secondaryair nozzle that is able to blow the air from the outside of the fuelnozzle; the flame stabilizer that is provided at the front end portionof the fuel nozzle so as to be near the axis center side of the fuelnozzle; and the rectification member that is provided between the innerwall surface of the fuel nozzle and the flame stabilizer, theappropriate flow of the fuel gas may be realized.

Further, according to the combustion burner of the invention, since thecombustion burner includes: the fuel nozzle that is able to blow thefuel gas obtained by mixing the solid fuel and the air; the secondaryair nozzle that is able to blow the air from the outside of the fuelnozzle; the flame stabilizer that is provided at the front end portionof the fuel nozzle so as to be near the axis center side of the fuelnozzle; and the guide member that guides the fuel gas flowing throughthe fuel nozzle toward the axis center side of the fuel nozzle, theappropriate flow of the fuel gas may be realized, and hence the innerflame stabilization performance may be improved.

Further, according to the solid-fuel-combustion burner and thesolid-fuel-combustion boiler of the invention, since the outlet openingof the fuel burner is equipped with the split member provided as theinner flame stabilization mechanism in a plurality of directions, thepassage of the pulverized fuel and the air may be divided and disturbednear the center of the outlet opening of the fuel burner in which thesplit members intersect each other, and hence the ignition surface isfurther finely divided by the split members. Accordingly, since theignition position is disposed near the center of the flame, the oxygenconcentration at the center thereof is relatively low. For this reason,the reduction inside the flame is promptly performed, and hence theamount of NOx finally discharged from the solid-fuel-combustion boileris reduced. Further, since the splitter is provided in a plurality ofdirections, the inner air dispersion is promoted, and hence it ispossible to suppress the unburned combustible content caused by thelocally and extremely insufficient oxygen inside the flame.

That is, the hot oxygen remaining zone formed at the outer periphery ofthe flame is suppressed, and hence the final NOx production amount ofNOx discharged from the additional air input unit may be reduced. Inother words, since the hot oxygen remaining zone formed at the outerperiphery of the flame is suppressed, the NOx produced inside the flamegenerated by the pre-mixture combustion is effectively reduced.Accordingly, it is possible to obtain a remarkable advantage in whichthe final NOx amount decreases due to a decrease in the NOx amountreaching the additional air input unit and a decrease in the NOx amountproduced by the input of the additional air.

Further, according to the solid-fuel-combustion burner and thesolid-fuel-combustion boiler of the invention, since the outlet openingof the fuel burner is equipped with the split member provided as theinner flame stabilization mechanism in a plurality of directions, thepassage of the pulverized fuel and the air may be divided and disturbednear the center of the outlet opening of the fuel burner in which thesplit members intersect each other, and hence the ignition surface isfurther finely divided by the split members. Accordingly, since theignition position is disposed near the center of the flame, the oxygenconcentration at the center thereof is relatively low. For this reason,the reduction inside the flame is promptly performed, and hence theamount of NOx finally discharged from the solid-fuel-combustion boileris reduced. Further, since the splitter is provided in a plurality ofdirections, the inner air dispersion is promoted, and hence it ispossible to suppress the unburned combustible content caused by thelocally and extremely insufficient oxygen inside the flame.

That is, the hot oxygen remaining zone formed at the outer periphery ofthe flame is suppressed, and hence the final NOx production amount ofNOx discharged from the additional air input unit may be reduced. Inother words, since the hot oxygen remaining zone formed at the outerperiphery of the flame is suppressed, the NOx produced inside the flamegenerated by the pre-mixture combustion is effectively reduced.Accordingly, it is possible to obtain a remarkable advantage in whichthe final NOx amount decreases due to a decrease in the NOx amountreaching the additional air input unit and a decrease in the NOx amountproduced by the input of the additional air.

Further, according to the boiler and the method for operating the boilerof the invention, since the distribution of the secondary air and thetertiary air and the additional air, and the like is adjusted inresponse to the volatile content of the solid fuel, it is possible toimprove the operation efficiency by appropriately burning the solid fueland the volatile content contained in the solid fuel.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a front view illustrating a combustion burner according to afirst embodiment of the invention.

FIG. 2 is a cross-sectional view illustrating the combustion burner ofthe first embodiment.

FIG. 3 is a cross-sectional view illustrating a modified example of thecombustion burner of the first embodiment.

FIG. 4 is a cross-sectional view illustrating a modified example of thecombustion burner of the first embodiment.

FIG. 5 is a front view illustrating a modified example of the combustionburner of the first embodiment.

FIG. 6 is a cross-sectional view illustrating a modified example of thecombustion burner of the first embodiment.

FIG. 7 is a cross-sectional view illustrating a modified example of thecombustion burner of the first embodiment.

FIG. 8 is a front view illustrating a modified example of the combustionburner of the first embodiment.

FIG. 9 is a schematic configuration diagram illustrating apulverized-coal-combustion boiler that employs the combustion burner ofthe first embodiment.

FIG. 10 is a plan view illustrating a combustion burner of thepulverized-coal-combustion boiler of the first embodiment.

FIG. 11 is a cross-sectional view illustrating a combustion burneraccording to a second embodiment of the invention.

FIG. 12 is a cross-sectional view illustrating a combustion burneraccording to a third embodiment of the invention.

FIG. 13 is a cross-sectional view illustrating a combustion burneraccording to a fourth embodiment of the invention.

FIG. 14 is a cross-sectional view illustrating a combustion burneraccording to a fifth embodiment of the invention.

FIG. 15 is a cross-sectional view illustrating a combustion burneraccording to a sixth embodiment of the invention.

FIG. 16 is a front view illustrating a combustion burner according to aseventh embodiment of the invention.

FIG. 17 is a cross-sectional view illustrating the combustion burner ofthe seventh embodiment.

FIG. 18 is a schematic configuration diagram illustrating apulverized-coal-combustion boiler that employs the combustion burner ofthe seventh embodiment.

FIG. 19 is a plan view illustrating a combustion burner of thepulverized-coal-combustion boiler of the seventh embodiment.

FIG. 20 is a cross-sectional view illustrating a combustion burneraccording to an eighth embodiment of the invention.

FIG. 21 is a front view illustrating a combustion burner according to aninth embodiment of the invention.

FIG. 22 is a front view illustrating a combustion burner according to atenth embodiment of the invention.

FIG. 23 is a cross-sectional view illustrating a combustion burneraccording to an eleventh embodiment of the invention.

FIG. 24 is a cross-sectional view illustrating a modified example of thecombustion burner of the eleventh embodiment.

FIG. 25 is a diagram illustrating a twelfth embodiment relating to asolid-fuel-combustion (coal-fuel-combustion) burner according to theinvention, where FIG. 25(a) is a front view in which thesolid-fuel-combustion burner is seen from the inside of a furnace andFIG. 25(b) is a cross-sectional view taken along the line A-A of thesolid-fuel-combustion burner illustrated in FIG. 25(a) (a longitudinalsectional view of the solid-fuel-combustion burner).

FIG. 26 is a diagram illustrating an air supply system which suppliesair to the solid-fuel-combustion burner of FIG. 25.

FIG. 27 is a longitudinal sectional view illustrating a configurationexample of a solid-fuel-combustion (coal-combustion) boiler according tothe invention.

FIG. 28 is a transverse (horizontal) cross-sectional view of FIG. 24.

FIG. 29 is a diagram illustrating an outline of a solid-fuel-combustionboiler which includes an additional air input unit so as to input airthrough plural stages.

FIG. 30 is a diagram illustrating a split member of thesolid-fuel-combustion burner illustrated in FIG. 25, where FIG. 30(a) isa diagram illustrating an example of a cross-sectional shape of thesplit member, FIG. 30(b) is a diagram illustrating a first modifiedexample of the cross-sectional shape, FIG. 30(c) is a diagramillustrating a second modified example of the cross-sectional shape, andFIG. 30(d) is a diagram illustrating a third modified example of thecross-sectional shape.

FIG. 31 is a diagram illustrating a fourteenth embodiment relating to asolid-fuel-combustion (coal-fuel-combustion) burner according to theinvention, FIG. 31(a) is a front view in which the solid-fuel-combustionburner is seen from the inside of a furnace and FIG. 31(b) is across-sectional view taken along the line B-B of thesolid-fuel-combustion burner illustrated in FIG. 31(a) (a longitudinalsectional view of the solid-fuel-combustion burner).

FIG. 32(a) is a cross-sectional view taken along the line C-Cillustrating an example of one shape of a shielding member and FIG.32(b) is a cross-sectional view illustrating an example of the othershape of the shielding member illustrated in FIG. 32(a).

FIG. 33 is a diagram illustrating a fifteenth embodiment relating to asolid-fuel-combustion (coal-fuel-combustion) burner for a turningcombustion boiler according to the invention, where FIG. 33(a) is afront view in which the solid-fuel-combustion burner is seen from theinside of a furnace and FIG. 33(b) is a cross-sectional view taken alongthe line A-A of the solid-fuel-combustion burner illustrated in FIG.33(a) (a longitudinal sectional view of the solid-fuel-combustionburner).

FIG. 34 is a diagram illustrating an air supply system which suppliesair to the solid-fuel-combustion burner of FIG. 33.

FIG. 35 is a longitudinal sectional view illustrating a configurationexample of the solid-fuel-combustion boiler (coal-combustion boiler)according to the invention.

FIG. 36 is a transverse (horizontal) cross-sectional view of FIG. 35.

FIG. 37 is a diagram illustrating an outline of a solid-fuel-combustionboiler which includes an additional air input unit so as to input airthrough plural stages.

FIG. 38 is a diagram illustrating a split member of thesolid-fuel-combustion burner illustrated in FIG. 33, where FIG. 38(a) isa diagram illustrating an example of a cross-sectional shape, FIG. 38(b)is a diagram illustrating a first modified example of thecross-sectional shape, FIG. 38(c) is a diagram illustrating a secondmodified example of the cross-sectional shape, and FIG. 38(d) is adiagram illustrating a third modified example of the cross-sectionalshape.

FIG. 39 is a schematic configuration diagram illustrating apulverized-coal-combustion boiler as a boiler according to a seventeenthembodiment of the invention.

FIG. 40 is a plan view illustrating a combustion burner of thepulverized-coal-combustion boiler of the seventeenth embodiment.

FIG. 41 is a front view illustrating the combustion burner of theseventeenth embodiment.

FIG. 42 is a cross-sectional view illustrating the combustion burner ofthe seventeenth embodiment.

FIG. 43 is a graph illustrating a NOx production amount and an unburnedcombustible content production amount with respect to primary air andsecondary air.

DESCRIPTION OF EMBODIMENTS

Hereinafter, preferred embodiments of a combustion burner, asolid-fuel-combustion burner, a solid-fuel-combustion boiler, a boiler,and a method for operating the boiler of the invention will be describedin detail with reference to the accompanying drawings. Furthermore, theinvention is not limited to the embodiments, and also includes a casewhere the respective embodiments are combined with one another whenthere are plural embodiments.

First Embodiment

As a combustion burner of a conventional pulverized-coal-combustionboiler, the above-described combustion burner disclosed in PatentLiterature 1 is known. In the combustion device disclosed in PatentLiterature 1, the flame stabilizer is provided between the center insidethe pulverized coal ejecting hole (primary passage) and the outerperipheral portion thereof so that a pulverized coal condensed flow ismade to collide with the flame stabilizer. Accordingly, the low NOxcombustion may be stably performed in a broad load range.

However, in the conventional combustion device, when a fuel gas ofpulverized coal and air collides with the flame stabilizer, the flow isdivided at the rear end portion of the flame stabilizer, and hence theflame stabilization ability at the front end portion of the flamestabilizer may not be sufficiently exhibited. Further, in the vicinityof the flame stabilizer of the passage through which the fuel gas ofpulverized coal and air flows, the passage sectional area decreases dueto the arrangement of the flame stabilizer and the flow velocity of thefuel gas becomes faster than that of the upstream side thereof. Then,the flow velocity of the fuel gas becomes slow at the upstream side ofthe flame stabilizer, so that the pulverized coal contained in the fuelgas is deposited or attached to the lower portion of the passage.

A first embodiment solves this problem, and provides a combustion burnercapable of realizing an appropriate flow of a fuel gas obtained bymixing solid fuel and air.

FIG. 1 is a front view illustrating a combustion burner according to thefirst embodiment of the invention, FIG. 2 is a cross-sectional viewillustrating the combustion burner of the first embodiment, FIGS. 3 and4 are cross-sectional views illustrating modified examples of thecombustion burner of the first embodiment, FIG. 5 is a front viewillustrating a modified example of the combustion burner of the firstembodiment, FIGS. 6 and 7 are cross-sectional views illustratingmodified examples of the combustion burner of the first embodiment, FIG.8 is a front view illustrating a modified example of the combustionburner of the first embodiment, FIG. 9 is a schematic configurationdiagram illustrating a pulverized-coal-combustion boiler that employsthe combustion burner of the first embodiment, and FIG. 10 is a planview illustrating the combustion burner of thepulverized-coal-combustion boiler of the first embodiment.

The pulverized-coal-combustion boiler that employs the combustion burnerof the first embodiment is a boiler which uses pulverized coal obtainedby milling coal as solid fuel, burns the pulverized coal by a combustionburner, and collects heat generated by the combustion.

In the first embodiment, as illustrated in FIG. 9, apulverized-coal-combustion boiler 10 is a conventional boiler, andincludes a furnace 11 and a combustion device 12. The furnace 11 isformed in a hollow square cylindrical shape and is provided in thevertical direction, and the combustion device 12 is provided in thelower portion of the furnace wall forming the furnace 11.

The combustion device 12 includes plural combustion burners 21, 22, 23,24, and 25 which are attached to the furnace wall. In the embodiment,the combustion burners 21, 22, 23, 24, and 25 are disposed as one set inthe circumferential direction at four equal intervals therebetween, andfive sets, that is, five stages are disposed in the vertical direction.

Then, the respective combustion burners 21, 22, 23, 24, and 25 areconnected to coal pulverizers (mills) 31, 32, 33, 34, and 35 throughpulverized coal supply pipes 26, 27, 28, 29, and 30. Although notillustrated in the drawings, the coal pulverizers 31, 32, 33, 34, and 35have a configuration in which milling tables are supported in arotational driving state with rotation axes along the vertical directioninside a housing and plural milling rollers are provided while facingthe upper sides of the milling tables and are supported so as to berotatable along with the rotation of the milling tables. Accordingly,when coal is input between plural milling rollers and plural millingtables, the coal is milled into a predetermined size therein. Thus,pulverized coal which is classified by transportation air (primary air)may be supplied from pulverized coal supply pipes 26, 27, 28, 29, and 30to the combustion burners 21, 22, 23, 24, and 25.

Further, in the furnace 11, wind boxes 36 are provided at the attachmentpositions of the respective combustion burners 21, 22, 23, 24, and 25,where one end portion of an air duct 37 is connected to the wind box 36and an air blower 38 is attached to the other end portion of the airduct 37. Accordingly, combustion air (secondary air and tertiary air)sent by the air blower 38 may be supplied from the air supply pipe 37 tothe wind box 36, and may be supplied from the wind box 36 to each of thecombustion burners 21, 22, 23, 24, and 25.

For this reason, in the combustion device 12, the respective combustionburners 21, 22, 23, 24, and 25 may blow a pulverized fuel-air mixture(fuel gas) obtained by mixing pulverized coal and primary air into thefurnace 11 and may blow secondary air into the furnace 11. Then, a flamemay be formed by igniting the pulverized fuel-air mixture through anignition torch (not illustrated).

Furthermore, when generally activating the boiler, the respectivecombustion burners 21, 22, 23, 24, and 25 form a flame by ejecting oilfuel into the furnace 11.

A flue gas duct 40 is connected to the upper portion of the furnace 11,and the flue gas duct 40 is equipped with superheaters 41 and 42,repeaters 43 and 44, and economizers 45, 46, and 47 as convection heattransfer portions for collecting the heat of the flue gas. Accordingly,a heat exchange is performed between water and a flue gas that isproduced by the combustion in the furnace 11.

The downstream side of the flue gas duct 40 is connected with a flue gaspipe 48 into which the flue gas subjected to heat exchange isdischarged. An air heater 49 is provided between the flue gas pipe 48and the air duct 37, and a heat exchange is performed between the airflowing through the air duct 37 and the flue gas flowing through theflue gas pipe 48, so that the combustion air flowing through thecombustion burners 21, 22, 23, 24, and 25 may increase in temperature.

Furthermore, although not illustrated in the drawings, the flue gas pipe48 is equipped with a denitration device, an electronic precipitator, aninducing air blower, and a desulfurization device, and the downstreamend portion thereof is equipped with a stack.

Accordingly, when the coal pulverizers 31, 32, 33, 34, and 35 aredriven, pulverized coal produced therein is supplied along with thetransportation air to the combustion burners 21, 22, 23, 24, and 25through pulverized coal supply pipes 26, 27, 28, 29, and 30. Further,the heated combustion air is supplied from the air duct 37 to therespective combustion burners 21, 22, 23, 24, and 25 through the windboxes 36. Then, the combustion burners 21, 22, 23, 24, and 25 blow thepulverized fuel-air mixture obtained by mixing the pulverized coal andthe transportation air to the furnace 11, blow the combustion air to thefurnace 11, and ignite the pulverized fuel-air mixture and the air atthis time so as to form a flame. In the furnace 11, when the flame isgenerated by the combustion of the pulverized fuel-air mixture and thecombustion air and the flame is generated at the lower portion insidethe furnace 11, the combustion gas (the flue gas) rises inside thefurnace 11 so as to be discharged to the flue gas duct 40.

Furthermore, the inside of the furnace 11 is maintained at the reductionatmosphere in a manner such that the air supply amount with respect tothe pulverized coal supply amount becomes smaller than the theoreticalair amount. Then, when NOx produced by the combustion of the pulverizedcoal is reduced in the furnace 11 and additional air is additionallysupplied thereto, the oxidization combustion of the pulverized coal iscompleted and hence the production amount of NOx caused by thecombustion of the pulverized coal is reduced.

At this time, water supplied from a water feeding pump (not illustrated)is preheated by the economizers 45, 46, and 47, is supplied to a steamdrum (not illustrated), and is heated while being supplied to respectivewater pipes (not illustrated) of the furnace wall so as to becomesaturated steam. Then, the saturated steam is transported to a steamdrum (not illustrated). Further, the saturated steam of a steam drum(not illustrated) is introduced into the superheaters 41 and 42 and issuperheated by the combustion gas. The superheated steam produced by thesuperheaters 41 and 42 is supplied to a power generation plant (notillustrated) (for example, a turbine or the like). Further, the steamwhich is extracted during the expanding process in the turbine isintroduced into the repeaters 43 and 44, is superheated again, and isreturned to the turbine. Furthermore, the furnace 11 of a drum type(steam drum) has been described, but the invention is not limited to thestructure.

Subsequently, a harmful substance such as NOx is removed from the fluegas which passes through the economizers 45, 46, and 47 of the flue gasduct 40 by a catalyst of a denitration device (not illustrated) in theflue gas pipe 48, a particulate substance is removed therefrom by theelectronic precipitator, and a sulfur content is removed therefrom bythe desulfurization device. Then, the flue gas is discharged to theatmosphere through the stack.

Here, the combustion device 12 will be described in detail, but sincethe respective combustion burners 21, 22, 23, 24, and 25 constitutingthe combustion device 12 have substantially the same configuration, onlythe combustion burner 21 that is positioned at the uppermost stage willbe described.

As illustrated in FIG. 10, the combustion burner 21 includes thecombustion burners 21 a, 21 b, 21 c, and 21 d which are provided at fourwall surfaces of the furnace 11. The respective combustion burners 21 a,21 b, 21 c, and 21 d are connected with respective branch pipes 26 a, 26b, 26 c, and 26 d which are branched from a pulverized coal supply pipe26, and are connected with respective branch pipes 37 a, 37 b, 37 c, and37 d branched from the air duct 37.

Accordingly, the respective combustion burners 21 a, 21 b, 21 c, and 21d which are positioned at the respective wall surfaces of the furnace 11blow the pulverized fuel-air mixture obtained by mixing the pulverizedcoal and the transportation air to the furnace 11 and blow thecombustion air to the outside of the pulverized fuel-air mixture. Then,the pulverized fuel-air mixture is ignited from the respectivecombustion burners 21 a, 21 b, 21 c, and 21 d, so that four flames F1,F2, F3, and F4 may be formed. The flames F1, F2, F3, and F4 become aflame swirl flow that turns in the counter-clockwise direction whenviewed from the upside of the furnace 11 (in FIG. 10).

As illustrated in FIGS. 1 and 2, in the combustion burner 21 (21 a, 21b, 21 c, and 21 d) with such a configuration, the combustion burner isequipped with a fuel nozzle 51, a secondary air nozzle 52, and atertiary air nozzle 53 which are provided from the center side thereofand is equipped with a flame stabilizer 54. The fuel nozzle 51 may blowthe fuel gas (the pulverized fuel-air mixture) obtained by mixing thepulverized coal (the solid fuel) with the transportation air (theprimary air). The secondary air nozzle 52 is disposed at the outside ofthe first nozzle 51 and may blow the combustion air (the secondary air)to the outer peripheral side of the fuel gas ejected from the fuelnozzle 51. The tertiary air nozzle 53 is disposed at the outside of thesecondary air nozzle 52 and may blow the tertiary air to the outerperipheral side of the secondary air ejected from the secondary airnozzle 52.

Further, the flame stabilizer 54 is disposed inside the fuel nozzle 51so as to be positioned at the downstream side of the fuel gas blowingdirection and near the axis center, and serves to ignite and stabilizethe fuel gas. The flame stabilizer 54 is formed in a so-called doublecross split structure in which first flame stabilizing members 61 and 62following the horizontal direction and second flame stabilizing members63 and 64 following the vertical direction (the up and down direction)are disposed in a cross shape. Then, the respective first flamestabilizing members 61 and 62 include flat portions 61 a and 62 a eachformed in a flat plate shape having a uniform thickness and widenedportions 61 b and 62 b integrally formed with the front end portions ofthe flat portions 61 a and 62 a (the downstream end portions in the fuelgas flowing direction). Each cross-section of the widened portions 61 band 62 b is formed in an isosceles triangular shape, each width of thewidened portions is widened toward the downstream side in the fuel gasflowing direction, and each front end thereof is formed as a planeperpendicular to the fuel gas flowing direction. Furthermore, althoughnot illustrated in the drawings, the respective second flame stabilizingmembers 63 and 64 also have the same structure.

For this reason, each of the fuel nozzle 51 and the secondary air nozzle52 has an elongated tubular shape, the fuel nozzle 51 includes arectangular opening portion 51 a, and the secondary air nozzle 52includes a rectangular annular opening portion 52 a. Thus, the fuelnozzle 51 and the secondary air nozzle 52 are formed as a double tubestructure. The tertiary air nozzle 53 is disposed as a double tubestructure at the outside of the fuel nozzle 51 and the secondary airnozzle 52, and includes a rectangular annular opening portion 53 a. As aresult, the opening portion 52 a of the secondary air nozzle 52 isdisposed at the outside of the opening portion 51 a of the fuel nozzle51, and the opening portion 53 a of the tertiary air nozzle 53 isdisposed at the outside of the opening portion 52 a of the secondary airnozzle 52. Furthermore, the tertiary air nozzle 53 may not be disposedas a double tube structure, and the tertiary air nozzle may be obtainedby separately disposing plural nozzles at the outer peripheral side ofthe secondary air nozzle 52.

In the nozzles 51, 52, and 53, the opening portions 51 a, 52 a, and 53 aare disposed so as to be flush with one another. Further, the flamestabilizer 54 is supported by the inner wall surface of the fuel nozzle51 or a plate member (not illustrated) from the upstream side of thepassage through which the fuel gas flows. Further, since plural flamestabilizing members 61, 62, 63, and 64 are disposed as the flamestabilizer 54 inside the fuel nozzle 51, the fuel gas passage is dividedinto nine segments. Then, in the flame stabilizer 54, the widenedportions 61 b and 62 b of which the widths are wide are positioned atthe front end portions thereof, and the front end surfaces of thewidened portions 61 b and 62 b are evenly disposed so as to be flushwith the opening portion 51 a.

Further, in the combustion burner 21 of the first embodiment, arectification member 55 is provided between the inner wall surface ofthe fuel nozzle 51 and the flame stabilizer 54. The rectification member55 is disposed so as to have a predetermined gap with respect to theinner wall surface of the fuel nozzle 51 and have a predetermined gapwith respect to the flame stabilizer 54.

That is, the rectification member 55 is formed in a structure in whichfirst rectification members 65 and 66 following the horizontal directionand second rectification members 67 and 68 following the verticaldirection (the up and down direction) are disposed so as to form a frameshape. That is, the first rectification member 65 is positioned betweenthe upper wall of the fuel nozzle 51 and the first flame stabilizingmember 61, and the first rectification member 66 is positioned betweenthe lower wall of the fuel nozzle 51 and the first flame stabilizingmember 62. Further, the second rectification member 67 is positionedbetween the side wall (in FIG. 1, the left wall) of the fuel nozzle 51and the second flame stabilizing member 63, and the second rectificationmember 68 is positioned between the side wall (in FIG. 1, the rightwall) of the fuel nozzle 51 and the second flame stabilizing member 64.

Then, the respective first rectification members 65 and 66 include flatportions 65 a and 66 a which are formed in a flat plate shape having auniform thickness and tapered portions 65 b and 66 b which areintegrally formed with the front end portions of the flat portions 65 aand 66 a (the downstream end portions in the fuel gas flowingdirection). Each cross-section of the tapered portions 65 b and 66 b isformed in an isosceles triangular shape, each width of the taperedportions is narrowed toward the downstream side in the fuel gas flowingdirection, and each front end thereof becomes an acute angle.Furthermore, although not illustrated in the drawings, the respectivesecond rectification members 67 and 68 also have the same structure.

In this case, the respective flame stabilizing members 61, 62, 63, and64 and the respective rectification members 65, 66, 67, and 68 havesubstantially the same length in the fuel gas flowing direction, and aredisposed so as to face one another in a direction perpendicular to thefuel gas flowing direction. Furthermore, in the respective flamestabilizing members 61, 62, 63, and 64 and the respective rectificationmembers 65, 66, 67, and 68, the widened portions 61 b and 62 b and thetapered portions 65 b and 66 b also have substantially the same lengthin the fuel gas flowing direction, and are disposed so as to face oneanother in a direction perpendicular to the fuel gas flowing direction.

Since the flame stabilizer 54 and the rectification member 55 are formedin a shape equipped with the widened portions 61 b and 62 b and thetapered portions 65 b and 66 b, the distance between the flamestabilizer 54 and the rectification member 55 in the fuel gas flowingdirection is substantially equal in the fuel gas flowing direction.

Accordingly, in the combustion burner 21, the fuel gas obtained bymixing the pulverized coal with the primary air blows from the openingportion 51 a of the fuel nozzle 51 into the furnace, the secondary airat the outside thereof blows from the opening portion 52 a of thesecondary air nozzle 52 into the furnace, and the tertiary air at theoutside thereof blows from the opening portion 53 a of the tertiary airnozzle 53 into the furnace. At this time, the fuel gas is divided by theflame stabilizer 54 at the opening portion 51 a of the fuel nozzle 51,is ignited, and is burned so as to become a combustion gas. Further,since the secondary air blows to the outer periphery of the fuel gas,the combustion of the fuel gas is promoted. Further, since the tertiaryair blows to the outer periphery of the combustion flame, the combustionmay be optimally performed by adjusting the ratio between the secondaryair and the tertiary air.

Then, since the flame stabilizer 54 is formed in a split shape in thecombustion burner 21, the fuel gas is divided by the flame stabilizer 54at the opening portion 51 a of the fuel nozzle 51. At this time, theflame stabilizer 54 is disposed at the center zone of the openingportion 51 a of the fuel nozzle 51, and the fuel gas is ignited andstabilized at the center zone. Thus, the inner flame stabilization (theflame stabilization at the center zone of the opening portion 51 a ofthe fuel nozzle 51) of the combustion flame is realized.

For this reason, compared to the configuration in which the outer flamestabilization of the combustion flame is performed, the temperature ofthe outer peripheral portion of the combustion flame becomes low, andhence the temperature of the outer peripheral portion of the combustionflame under the high oxygen atmosphere by the secondary air may becomelow. Thus, the NOx production amount at the outer peripheral portion ofthe combustion flame is reduced.

Further, since the combustion burner 21 employs a configuration in whichthe inner flame stabilization is performed, it is desirable to supplythe fuel gas and the combustion air (the secondary air and the tertiaryair) as a straight flow. That is, it is desirable that the fuel nozzle51 have a structure in which the secondary air nozzle 52 and thetertiary air nozzle 53 supply the fuel gas, the secondary air, and thetertiary air as a straight flow instead of a swirl flow. Since the fuelgas, the secondary air, and the tertiary air are ejected as the straightflow so as to form the combustion flame, the circulation of the gasinside the combustion flame is suppressed in the configuration in whichthe inner flame stabilization of the combustion flame is performed.Accordingly, the outer peripheral portion of the combustion flame ismaintained in a low temperature, and the NOx production amount caused bythe mixture with the secondary air is reduced.

Further, in the combustion burner 21, the rectification member 55 isdisposed between the fuel nozzle 51 and the flame stabilizer 54 so as tohave a predetermined gap therebetween. For this reason, since the fuelgas particularly flowing between the flame stabilizer 54 and therectification member 55 is rectified, the division of the fuel gas doesnot occur at the rear end portion of the flame stabilizer 54, and thefuel gas flow directed to the front end portion is formed. For thisreason, the flame stabilizer 54 may ensure a sufficient flamestabilization ability at the front end portion thereof.

Further, since the front end portion of the flame stabilizer 54 isequipped with the widened portions 61 b and 62 b and the front endportion of the rectification member 55 is equipped with the taperedportions 65 b and 66 b, the passage which is formed between the flamestabilizer 54 and the rectification member 55 has substantially the samepassage sectional area in the longitudinal direction. Thus, the flowvelocity of the fuel gas flowing through the passage becomes uniform,and the flow velocity of the fuel gas decreases on the whole.Accordingly, the flame stabilizer 54 may ensure a sufficient flamestabilization ability at the front end portion thereof. Further, in thepulverized-coal-combustion boiler, the steam temperature or the flue gascharacteristics needs to be adjusted, and even at this time, the innerflame stabilization may be ensured by the rectification member 55.

Furthermore, in the combustion burner 21, the configurations of theflame stabilizer 54 and the rectification member 55 are not limited tothose of the above-described embodiment.

For example, as illustrated in FIG. 3, the combustion burner 21 isequipped with the fuel nozzle 51, the secondary air nozzle 52, and thetertiary air nozzle 53 which are provided from the center side of thecombustion burner, and is equipped with a flame stabilizer 71. The flamestabilizer 71 is disposed inside the fuel nozzle 51 so as to bepositioned at the downstream side in the fuel gas blowing direction andnear the axis center, and serves to ignite and stabilize the fuel gas.The flame stabilizer 71 is formed in a so-called double cross splitstructure in which first flame stabilizing members 72 and 73 followingthe horizontal direction and second flame stabilizing members (notillustrated) following the vertical direction are disposed in a crossshape. Then, each cross-section of the first flame stabilizing members72 and 73 is formed in an isosceles triangular shape, each width of thefirst flame stabilizing members is widened toward the downstream side inthe fuel gas flowing direction, and each front end thereof is formed asa plane perpendicular to the fuel gas flowing direction. Furthermore,the respective second flame stabilizing members also have the samestructure.

Accordingly, since the fuel gas is divided by the flame stabilizer 71 atthe opening portion 51 a of the fuel nozzle 51, the inner flamestabilization of the combustion flame may be performed by the fuel gasgoing round to the front end surface side of the flame stabilizer, andthe temperature of the outer peripheral portion of the combustion flameunder a high oxygen atmosphere becomes low by the secondary air. Thus,the NOx production amount in the outer peripheral portion of thecombustion flame is reduced. Further, at this time, since the fuel gasflowing between the rectification member 55 and the flame stabilizer 71is rectified by the rectification member, the separation of the fuel gasdisappears. Further, the flow velocity of the fuel gas flowingtherethrough becomes uniform, and the flow velocity thereof is reduced.For this reason, the flame stabilizer 71 may ensure a sufficient flamestabilization ability at the front end portion thereof.

Further, as illustrated in FIG. 4, the combustion burner 21 is equippedwith the fuel nozzle 51, the secondary air nozzle 52, and the tertiaryair nozzle 53 which are provided from the center side of the combustionburner, and is equipped with the flame stabilizer 54 Then, arectification member 75 is provided between the inner wall surface ofthe fuel nozzle 51 and the flame stabilizer 54. The rectification member75 is disposed so as to have a predetermined gap with respect to theinner wall surface of the fuel nozzle 51 and have a predetermined gapwith respect to the flame stabilizer 54. That is, the rectificationmember 75 is formed in a structure in which first rectification members76 and 77 following the horizontal direction and second rectificationmembers (not illustrated) following the vertical direction (the up anddown direction) are disposed so as to form a frame shape. Then, each ofthe first rectification members 76 and 77 is formed in a flat plateshape of which the thickness is uniform. Furthermore, the respectivesecond rectification members also have the same structure.

In this case, the lengths of the respective rectification members 76 and77 are slightly shorter than those of the respective flame stabilizingmembers 61 and 62 in the fuel gas flowing direction, and the respectiverectification members and the respective flame stabilizing members aredisposed so as to face one another in a direction perpendicular to thefuel gas flowing direction. That is, the flat portions 61 a and 62 a ofthe respective flame stabilizing members 61 and 62 and the respectiverectification members 76 and 77 have substantially the same length inthe fuel gas flowing direction.

Since the flame stabilizer 54 and the rectification member 75 are formedin a shape equipped with the widened portions 61 b and 62 b, thedistance between the flame stabilizer 54 and the rectification member 75in a direction perpendicular to the fuel gas flowing direction issubstantially equal in the fuel gas flowing direction. Then, in theflame stabilizer 54, the widened portions 61 b and 62 b are provided atthe downstream side in the fuel gas flowing direction, and therectification member 75 is provided at a position where therectification member does not face the widened portions 61 b and 62 b.

Accordingly, since the fuel gas is divided by the flame stabilizer 54 atthe opening portion of the fuel nozzle 51, the inner flame stabilizationof the combustion flame may be performed by the fuel gas going round tothe front end surface side of the flame stabilizer, and the temperatureof the outer peripheral portion of the combustion flame under a highoxygen atmosphere becomes low by the secondary air. Thus, the NOxproduction amount of the outer peripheral portion of the combustionflame is reduced. Further, at this time, since the fuel gas flowingbetween the rectification member 75 and the flame stabilizer 54 isrectified by the rectification member, the separation of the fuel gasdisappears. Further, the flow velocity of the fuel gas flowingtherethrough becomes uniform, and the flow velocity thereof is reduced.For this reason, the flame stabilizer 54 may ensure the sufficient flamestabilization ability at the front end portion thereof.

Further, as illustrated in FIG. 5, the combustion burner 21 is equippedwith the fuel nozzle 51, the secondary air nozzle 52, and the tertiaryair nozzle 53, and is equipped with a flame stabilizer 81. Then, arectification member 55 is provided between the inner wall surface ofthe fuel nozzle 51 and the flame stabilizer 81. The flame stabilizer 81is disposed inside the fuel nozzle 51 so as to be positioned at thedownstream side in the fuel gas blowing direction and near the axiscenter, and serves to ignite and stabilize the fuel gas. The flamestabilizer 81 is formed in a so-called double cross split structure inwhich first flame stabilizing members 82 and 83 following the horizontaldirection and second flame stabilizing members 84 and 85 following thevertical direction are disposed in a cross shape. Then, the widths ofthe first flame stabilizing members 82 and 83 are set to be larger thanthose of the second flame stabilizing members 84 and 85.

Accordingly, since the fuel gas is divided by the flame stabilizer 81 atthe opening portion 51 a of the fuel nozzle 51, the inner flamestabilization of the combustion flame may be performed by the fuel gasgoing round to the front end surface side of the flame stabilizer, andthe temperature of the outer peripheral portion of the combustion flameunder a high oxygen atmosphere becomes low by the secondary air. Thus,the NOx production amount in the outer peripheral portion of thecombustion flame is reduced. In this case, since the widths of the firstflame stabilizing members 82 and 83 are larger than those of the secondflame stabilizing members 84 and 85, the first flame stabilizing members82 and 83 have the higher flame stabilizing abilities than those of thesecond flame stabilizing members 84 and 85. Since the burner 21 of theembodiment is of a turning combustion type and the air is supplied fromthe upper and lower sides of the fuel gas, it is effective to ensure ahigh flame stabilization ability in the horizontal direction for theinner flame stabilization.

Here, since the widths of the first flame stabilizing members 82 and 83following the horizontal direction are set to be larger than those ofthe second flame stabilizing members 84 and 85 following the verticaldirection, it is possible to improve the flame stabilizing function inthe horizontal direction by the first flame stabilizing members 82 and83 having wide widths. Meanwhile, the widths of the second flamestabilizing members 84 and 85 following the vertical direction may beset to be larger than those of the first flame stabilizing members 82and 83 following the horizontal direction. In this case, it is possibleto improve the flame stabilizing function without the adverse influenceof the second flame stabilizing members 84 and 85 when the direction ofthe fuel nozzle 51 swings up and down for the steam temperature controlor the like. This is because of the following reasons. When the fuelnozzle 51 moves up and down, the position of the flame stabilizingmember with respect to the fuel gas blowing position largely changes inthe first flame stabilizing members 82 and 83, but substantially doesnot change in the second flame stabilizing members 84 and 85.

Further, as illustrated in FIG. 6, the combustion burner 21 is equippedwith the fuel nozzle 51, the secondary air nozzle 52, and the tertiaryair nozzle 53 which are provided from the center side of the combustionburner, and is equipped with a flame stabilizer 91. The flame stabilizer91 is disposed inside the fuel nozzle 51 so as to be positioned at thedownstream side in the fuel gas blowing direction and near the axiscenter, and serves to ignite and stabilize the fuel gas. The flamestabilizer 91 is formed in a so-called double cross split structure inwhich first flame stabilizing members 92 and 93 following the horizontaldirection and second flame stabilizing members (not illustrated)following the vertical direction are disposed in a cross shape. Then,the first flame stabilizing members 92 and 93 include flat portions 92 aand 93 a, widened portions 92 b and 93 b, and tapered portions 92 c and93 c, and the tapered portions 92 c and 93 c are provided in the rearend portion thereof so that the widths thereof are narrowed toward theupstream side in the fuel gas flowing direction. Furthermore, therespective second flame stabilizing members also have the samestructure.

Then, a rectification member 95 is provided between the inner wallsurface of the fuel nozzle 51 and the flame stabilizer 91. Therectification member 95 is disposed so as to have a predetermined gapwith respect to the inner wall surface of the fuel nozzle 51 and have apredetermined gap with respect to the flame stabilizer 91. That is, therectification member 95 is formed in a structure in which firstrectification members 96 and 97 following the horizontal direction andsecond rectification members (not illustrated) following the verticaldirection (the up and down direction) are disposed so as to form a frameshape. Then, the respective first rectification members 96 and 97include flat portions 96 a and 97 a, tapered portions 96 b and 97 b, andtapered portions 96 c and 97 c, and the tapered portions 96 c and 97 care provided in the rear end portion so that the widths thereof arenarrowed toward the upstream side in the fuel gas flowing direction.Furthermore, the respective second rectification members also have thesame structure.

Accordingly, since the fuel gas is divided by the flame stabilizer 91 atthe opening portion 51 a of the fuel nozzle 51, the inner flamestabilization of the combustion flame may be performed by the fuel gasgoing round to the front end surface side of the flame stabilizer, andthe temperature of the outer peripheral portion of the combustion flameunder a high oxygen atmosphere becomes low by the secondary air. Thus,the NOx production amount in the outer peripheral portion of thecombustion flame is reduced. Further, at this time, since the fuel gasflowing between the rectification member 95 and the flame stabilizer 91is rectified by the rectification member, the separation of the fuel gasdisappears. Further, the flow velocity of the fuel gas flowingtherethrough becomes uniform, and the flow velocity thereof is reduced.For this reason, the flame stabilizer 91 may ensure a sufficient flamestabilization ability at the front end portion thereof. Further, sincethe flame stabilizer 91 and the rectification member 95 are equippedwith the tapered portions 92 c, 93 c, 96 c, and 97 c, the fuel gassmoothly flows along the flame stabilizer 91 or the rectification member95, and hence the division thereof is suppressed

Further, as illustrated in FIG. 7, the combustion burner 21 is equippedwith the fuel nozzle 51, the secondary air nozzle 52, and the tertiaryair nozzle 53 which are provided from the center side of the combustionburner, and is equipped with the flame stabilizer 54. Then, arectification member 101 is provided between the inner wall surface ofthe fuel nozzle 51 and the flame stabilizer 54. The rectification member101 is disposed so as to have a predetermined gap with respect to theinner wall surface of the fuel nozzle 51 and have a predetermined gapwith respect to the flame stabilizer 54. That is, the rectificationmember 101 is formed in a structure in which first rectification members102 and 103 following the horizontal direction and second rectificationmembers (not illustrated) following the vertical direction (the up anddown direction) are disposed so as to form a frame shape. Then, therespective first rectification members 102 and 103 include flat portions102 a and 103 a which are formed in a flat plate shape having a uniformthickness and widened portions 102 b and 103 b which are integrallyformed with the front end portions (the downstream end portions in thefuel gas flowing direction). Furthermore, the respective secondrectification members also have the same structure.

In this case, the lengths of the respective rectification members 102and 103 are slightly shorter than those of the respective flamestabilizing members 61 and 62 in the fuel gas flowing direction, and therespective rectification members and the respective flame stabilizingmembers are disposed so as to face one another in a directionperpendicular to the fuel gas flowing direction. That is, the flatportions 61 a and 62 a of the respective flame stabilizing members 61and 62 and the respective rectification members 102 and 103 havesubstantially the same length in the fuel gas flowing direction.

Accordingly, since the fuel gas is divided by the flame stabilizer 54 atthe opening portion of the fuel nozzle 51, the inner flame stabilizationof the combustion flame may be performed by the fuel gas going round tothe front end surface side of the flame stabilizer, the temperature ofthe outer peripheral portion of the combustion flame under a high oxygenatmosphere becomes low by the secondary air, and the NOx productionamount in the outer peripheral portion of the combustion flame isreduced. Further, at this time, since the fuel gas flowing between therectification member 101 and the flame stabilizer 54 is rectified by therectification member, the separation of the fuel gas disappears.Further, the flow velocity of the fuel gas flowing therethrough becomesuniform, and the flow velocity thereof is reduced. Thus, the flamestabilizer 54 may ensure a sufficient flame stabilization ability at thefront end portion thereof. Further, since the rectification member 101is shorter than the flame stabilizer 54, even when the widened portions102 b and 103 b are provided at the front end portions thereof so as tohave a flame stabilizing function, the flame stabilization ability maybe improved without extremely narrowing the passage sectional area ofthe fuel nozzle 51, and hence even a flame-resistant fuel may be stablyburned.

Further, as illustrated in FIG. 8, the combustion burner 21 is equippedwith a fuel nozzle 111, a secondary air nozzle 112, and a tertiary airnozzle 113 which are provided from the center side of the combustionburner, and is equipped with a flame stabilizer 114. Then, arectification member 115 is provided between the inner wall surface ofthe fuel nozzle 111 and the flame stabilizer 114. In this case, the fuelnozzle 111 includes a circular opening portion, and the secondary airnozzle 112 and the tertiary air nozzle 113 also have the samecylindrical shape. Such a configuration is particularly applied to aconfiguration in which the combustion burner 21 is disposed in anopposing manner.

The flame stabilizer 114 is disposed inside the fuel nozzle 111 so as tobe positioned at the downstream side in the fuel gas blowing directionand near the axis center, and serves to ignite and stabilize the fuelgas. The flame stabilizer 114 is disposed so that two flame stabilizingmembers following the horizontal direction intersect two flamestabilizing members following the vertical direction. Further, therectification member 115 is disposed so as to have a predetermined gapwith respect to the inner wall surface of the fuel nozzle 111 and have apredetermined gap with respect to the flame stabilizer 114. That is, therectification member 115 is formed in a structure in which tworectification members following the horizontal direction and tworectification members following the vertical direction are disposed soas to form a frame shape.

Accordingly, since the fuel gas is divided by the flame stabilizer 114at the opening portion of the fuel nozzle 111, the inner flamestabilization of the combustion flame may be performed by the fuel gasgoing round to the front end surface side of the flame stabilizer, thetemperature of the outer peripheral portion of the combustion flameunder a high oxygen atmosphere becomes low by the secondary air, and theNOx production amount in the outer peripheral portion of the combustionflame is reduced. Further, at this time, since the fuel gas flowingbetween the rectification member 115 and the flame stabilizer 114 isrectified by the rectification member, the separation of the fuel gasdisappears. Further, the flow velocity of the fuel gas flowingtherethrough becomes uniform, and the flow velocity thereof is reduced.Thus, the flame stabilizer 114 may ensure a sufficient flamestabilization ability at the front end portion thereof.

In this way, the combustion burner of the first embodiment includes thefuel nozzle 51 which may blow the fuel gas obtained by mixing thepulverized coal with the primary air and the secondary air nozzle 52which may blow the secondary air from the outside of the fuel nozzle 51,the flame stabilizer 54 is provided at the front end portion of the fuelnozzle 51 so as to be near the axis center, and the rectification member55 is provided between the inner wall surface of the fuel nozzle 51 andthe flame stabilizer 54.

Accordingly, since the rectification member 55 is provided between theinner wall surface of the fuel nozzle 51 and the flame stabilizer 54,the flow of the fuel gas flowing through the fuel nozzle 51 is rectifiedby the rectification member 55, and hence the division of the flow ofthe fuel gas at the rear end portion of the flame stabilizer 54 issuppressed. Also, since the flow velocity becomes substantially uniform,the deposit (or the attachment) of the pulverized coal fuel to the innerwall surface of the fuel nozzle 51 is suppressed. Thus, the appropriateflow of the fuel gas may be realized.

Further, in the combustion burner of the first embodiment, therectification member 55 is disposed so as to have a predetermined gapwith respect to the flame stabilizer 54. Accordingly, since apredetermined gap is ensured between the rectification member 55 and theflame stabilizer 54, the flow of the fuel gas flowing between therectification member 55 and the flame stabilizer 54 is rectified, andthe fuel gas is appropriately introduced into the flame stabilizer 54.Thus, the flame stabilizing function may be sufficiently exhibited bythe flame stabilizer 54.

Further, in the combustion burner of the first embodiment, the distancebetween the flame stabilizer 54 and the rectification member 55 in thefuel gas flowing direction becomes substantially uniform by therectification member 55. Accordingly, since the distance between therectification member 55 and the flame stabilizer 54 in the fuel gasflowing direction becomes substantially uniform by the rectificationmember, the flow velocity of the fuel gas flowing between therectification member 55 and the flame stabilizer 54 becomessubstantially uniform, and hence the deposit of the pulverized coal fuelof the fuel nozzle 51 or the attachment of the pulverized coal fuel tothe flame stabilizer 54 may be suppressed.

Further, in the combustion burner of the first embodiment, the widenedportions 61 b and 62 b are provided at the downstream side in the fuelgas flowing direction of the flame stabilizer 54, and the taperedportions 65 b and 66 b are provided at the downstream side in the fuelgas flowing direction of the rectification member 55. Accordingly, sincethe front end portion of the flame stabilizer 54 is equipped with thewidened portions 61 b and 62 b, the flame may be reliably stabilized.Then, since the front end portion of the rectification member 55 isequipped with the tapered portions 65 b and 66 b, the distance betweenthe flame stabilizer 54 and the rectification member 55 in the fuel gasflowing direction may become substantially uniform.

Further, in the combustion burner of the first embodiment, the flamestabilizer 54 is formed in a structure in which two first flamestabilizing members 61 and 62 provided in the horizontal direction whilebeing parallel to each other in the vertical direction with apredetermined gap therebetween and two second flame stabilizing members63 and 64 provided in the vertical direction while being parallel toeach other in the horizontal direction with a predetermined gaptherebetween are disposed so as to intersect one another. Accordingly,since the flame stabilizer 54 is formed in a double cross structure, asufficient flame stabilizing function may be ensured.

Further, in the combustion burner of the first embodiment, the widenedportions 61 b and 62 b are provided at the downstream side in the fuelgas flowing direction of the flame stabilizer 54, and the rectificationmember 75 is provided at a position where the rectification member doesnot face the widened portions 61 b and 62 b. Accordingly, since therectification member 75 is provided at a position where therectification member does not face the widened portions 61 b and 62 b ofthe flame stabilizer 54, the flow velocity of the fuel gas becomessubstantially uniform without narrowing the fuel gas passages betweenthe fuel nozzle 51 and the widened portions 61 b and 62 b of the flamestabilizer 54, and hence the deposit of the pulverized coal fuel of thefuel nozzle 51 or the attachment of the pulverized coal fuel to theflame stabilizer 54 may be suppressed.

Second Embodiment

FIG. 11 is a cross-sectional view illustrating a combustion burneraccording to a second embodiment of the invention. Furthermore, the samereference sign will be given to the component having the same functionas that of the above-described embodiment, and the detailed descriptionthereof will not be repeated.

In the combustion burner of the second embodiment, as illustrated inFIG. 11, the combustion burner 21 is equipped with the fuel nozzle 51,the secondary air nozzle 52, and the tertiary air nozzle 53 which areprovided from the center side of the combustion burner, and is equippedwith a flame stabilizer 121. Then, a rectification member 122 isprovided between the inner wall surface of the fuel nozzle 51 and theflame stabilizer 121.

The flame stabilizer 121 is disposed at the axis center of the fuelnozzle 51 so as to follow the horizontal direction, and theconfiguration is substantially the same as those of the first flamestabilizing members 61 and 62 described in the first embodiment. Thatis, the flame stabilizer 121 includes a widened portion of which thewidth is widened toward the downstream side in the fuel gas flowingdirection, and the front end thereof becomes a plane perpendicular tothe fuel gas flowing direction.

Since the rectification member 122 is fixed along the inner wall surfaceof the fuel nozzle 51, the rectification member has a predetermined gapwith respect to the flame stabilizer 121. That is, the rectificationmember 122 includes first rectification members 123 and 124 followingthe horizontal direction, and the downstream end portion in the fuel gasflowing direction is equipped with inclined portions 123 a and 124 awhich face the upper and lower sides of the widened portion of the flamestabilizer 121. In this case, the first rectification members 123 and124 are directly fixed to the inner wall surface of the fuel nozzle 51,but a support member may extend from the upstream portion of the fuelnozzle 51 so as to support the first rectification members 123 and 124.

For this reason, the flame stabilizer 121 and the rectification member122 are formed in a shape in which the widened portion faces theinclined portions 123 a and 124 a, and the distance between the flamestabilizer 121 and the rectification member 122 in a directionperpendicular to the fuel gas flowing direction is substantially equalin the fuel gas flowing direction.

Accordingly, since the fuel gas is divided by the flame stabilizer 121at the opening portion 51 a of the fuel nozzle 51, the inner flamestabilization of the combustion flame may be performed by the fuel gasgoing round to the front end surface side of the flame stabilizer, thetemperature of the outer peripheral portion of the combustion flameunder a high oxygen atmosphere becomes low by the secondary air, and theNOx production amount in the outer peripheral portion of the combustionflame is reduced. Further, at this time, since the flow of the fuel gasflowing between the rectification member 122 and flame stabilizer 121 isrectified by the rectification member, the separation of the fuel gasdisappears. Further, the flow velocity of the fuel gas flowingtherethrough becomes uniform, and the flow velocity thereof is reduced.Thus, the flame stabilizer 121 may ensure a sufficient flamestabilization ability at the front end portion thereof.

In this way, in the combustion burner of the second embodiment, therectification member 122 is provided in the inner wall surface of thefuel nozzle 51. Accordingly, since the rectification member 122 isprovided in the inner wall surface of the fuel nozzle 51, a separateattachment member or the like is not needed. Accordingly, therectification member 122 may be simply supported. Thus, the assemblingworkability of the rectification member 122 may be improved, and themanufacturing cost may be reduced. Further, the mixing of the secondaryair may be delayed, and hence the outer peripheral zone with a hightemperature and a high oxygen concentration may be reduced.

Third Embodiment

FIG. 12 is a cross-sectional view illustrating a combustion burneraccording to a third embodiment of the invention. Furthermore, the samereference sign will be given to the component having the same functionas that of the above-described embodiment, and the detailed descriptionthereof will not be repeated.

In the combustion burner of the third embodiment, as illustrated in FIG.12, the combustion burner 21 is equipped with the fuel nozzle 51, thesecondary air nozzle 52, and the tertiary air nozzle 53 which areprovided from the center side of the combustion burner, and is equippedwith a flame stabilizer 131. Then, a rectification member 135 isprovided inside the flame stabilizer 131.

The flame stabilizer 131 is disposed at the axis center of the fuelnozzle 51 so as to follow the horizontal direction, and two flamestabilizing members following the horizontal direction and two flamestabilizing members following the vertical direction are disposed so asto intersect one another. Further, the rectification member 135 includesa first rectification member 136 which is positioned between therespective flame stabilizing members of the flame stabilizer 131 so asto be formed in a cross shape by the intersection in the horizontaldirection and the vertical direction and second rectification members137 and 138 which are positioned at the upstream side in relation to theflame stabilizer 131 and the rectification member 136 and are fixed tothe inner wall surface of the fuel nozzle 51.

Since the first rectification member 136 is fixed to the inner wallsurface of the fuel nozzle 51, the first rectification member has apredetermined gap with respect to the flame stabilizer 131. Further, thesecond rectification members 137 and 138 are fixed to the inner wallsurface of the fuel nozzle 51 at the upstream side of the fuel gas inrelation to the flame stabilizer 131, and hence the fuel gas flowingthrough the fuel nozzle 51 may be guided to the center side thereof.

Accordingly, since the fuel gas is divided by flame stabilizers 132 and133 at the fuel nozzle 51, the inner flame stabilization of thecombustion flame may be performed by the fuel gas going round to thefront end surface side of the flame stabilizer, the temperature of theouter peripheral portion of the combustion flame under a high oxygenatmosphere becomes low by the secondary air, and the NOx productionamount in the outer peripheral portion of the combustion flame isreduced. Further, at this time, since the fuel gas is guided toward thecenter side of the fuel nozzle 51 by the second rectification members137 and 138 and the fuel gas flowing between the first rectificationmember 136 and the flame stabilizer 132 is rectified by the firstrectification member, the separation of the fuel gas disappears, and inaddition, the flow velocity of the fuel gas flowing therethrough becomesuniform and is reduced. Thus, the flame stabilizer 132 may ensure asufficient flame stabilization ability at the front end portion thereof.

In this way, in the combustion burner of the third embodiment, as therectification member 135, there are provided the first rectificationmember 136 which is positioned inside the flame stabilizer 131 so as toform a cross shape and the second rectification members 137 and 138which are positioned at the upstream side in relation to the flamestabilizer 131. Accordingly, the fuel gas flowing through the fuelnozzle 51 is guided to the center side of the fuel nozzle 51 by thesecond rectification members 137 and 138, and the flow thereof isrectified by the first rectification member 136, so that the appropriateflow of the fuel gas may be realized.

Fourth Embodiment

FIG. 13 is a cross-sectional view illustrating a combustion burneraccording to a fourth embodiment of the invention. Furthermore, the samereference sign will be given to the component having the same functionas that of the above-described embodiment, and the detailed descriptionthereof will not be repeated.

In the combustion burner of the fourth embodiment, as illustrated inFIG. 13, the combustion burner 21 is equipped with the fuel nozzle 51,the secondary air nozzle 52, and the tertiary air nozzle 53 which areprovided from the center side of the combustion burner, and is equippedwith the flame stabilizer 54. Then, a rectification member 141 isprovided inside the flame stabilizer 54. The flame stabilizer 131 isdisposed at the axis center of the fuel nozzle 51 so as to follow thehorizontal direction. The rectification member 141 forms a cross shapeby the intersection of the horizontal direction and the verticaldirection inside the flame stabilizer 54. In this case, the front endportion of the rectification member 141 is positioned at the upstreamside in relation to the flame stabilizer 54.

Accordingly, since the fuel gas is divided by the flame stabilizer 54 atthe fuel nozzle 51, the inner flame stabilization of the combustionflame may be performed by the fuel gas going round to the front endsurface side of the flame stabilizer, the temperature of the outerperipheral portion of the combustion flame under a high oxygenatmosphere becomes low by the secondary air, and the NOx productionamount in the outer peripheral portion of the combustion flame isreduced. Further, at this time, since the fuel gas flowing between therectification member 141 and the flame stabilizer 54 is rectified by therectification member, the separation of the fuel gas disappears.Further, the flow velocity of the fuel gas flowing therethrough becomesuniform, and the flow velocity thereof is reduced. Thus, the flamestabilizer 54 may ensure a sufficient flame stabilization ability at thefront end portion thereof.

In this way, in the combustion burner of the fourth embodiment, therectification member 141 is provided inside the flame stabilizer 54 soas to be fixed to the inner wall surface of the fuel nozzle 51.Accordingly, the flow of the fuel gas flowing through the fuel nozzle 51is rectified by the rectification member 141, so that the appropriateflow of the fuel gas may be realized.

Fifth Embodiment

FIG. 14 is a cross-sectional view illustrating a combustion burneraccording to a fifth embodiment of the invention. Furthermore, the samereference sign will be given to the component having the same functionas that of the above-described embodiment, and the detailed descriptionthereof will not be repeated.

In the combustion burner of the fifth embodiment, as illustrated in FIG.14, the combustion burner 21 is equipped with the fuel nozzle 51, thesecondary air nozzle 52, and the tertiary air nozzle 53 which areprovided from the center side of the combustion burner, and is equippedwith the flame stabilizer 121. Then, a rectification member 151 isprovided between the inner wall surface of the fuel nozzle 51 and theflame stabilizer 121.

The flame stabilizer 121 is disposed at the axis center of the fuelnozzle 51 so as to follow the horizontal direction, and theconfiguration is substantially the same as those of the first flamestabilizing members 61 and 62 described in the first embodiment. Therectification member 151 is disposed so as to have a predetermined gapwith respect to the inner wall surface of the fuel nozzle 51 and have apredetermined gap with respect to the flame stabilizer 121. That is, therectification member 151 is formed in a structure in which firstrectification members 152 and 153 following the horizontal direction andsecond rectification members (not illustrated) following the verticaldirection (the up and down direction) are disposed so as to form a frameshape. Then, the respective first rectification members 152 and 153 aredisposed so that the front end portions thereof approach the flamestabilizer 121 and the rear end portions thereof are separated from theflame stabilizer 121. Furthermore, the respective second rectificationmembers also have the same structure.

In this case, since the front end portions of the respectiverectification members 152 and 153 approach the flame stabilizer 121, thegap between the rectification members 152 and 153 and the flamestabilizer 121 is narrowed as it goes toward the downstream side.

Accordingly, since the fuel gas is divided by the flame stabilizer 121at the opening portion of the fuel nozzle 51, the inner flamestabilization of the combustion flame may be performed by the fuel gasgoing round to the front end surface side of the flame stabilizer, thetemperature of the outer peripheral portion of the combustion flameunder a high oxygen atmosphere becomes low by the secondary air, and theNOx production amount in the outer peripheral portion of the combustionflame is reduced. Further, at this time, since the fuel gas flowingbetween the rectification member 151 and the flame stabilizer 121 isrectified by the rectification member, the separation of the fuel gasdisappears. Further, the flow velocity of the fuel gas flowingtherethrough becomes uniform, and the flow velocity thereof is reduced.Thus, the flame stabilizer 121 may ensure a sufficient flamestabilization ability at the front end portion thereof.

In this way, in the combustion burner of the fifth embodiment, therectification member 151 is provided outside the flame stabilizer 121 soas to be fixed to the inner wall surface of the fuel nozzle 51, and thefront end portion thereof is inclined so as to approach the flamestabilizer 121. Accordingly, the flow of the fuel gas flowing throughthe fuel nozzle 51 is rectified by the rectification member 151, so thatthe appropriate flow of the fuel gas may be realized.

Sixth Embodiment

FIG. 15 is a cross-sectional view illustrating a combustion burneraccording to a sixth embodiment of the invention. Furthermore, the samereference sign will be given to the component having the same functionas that of the above-described embodiment, and the detailed descriptionthereof will not be repeated.

In the combustion burner of the sixth embodiment, as illustrated in FIG.15, the combustion burner 21 is equipped with the fuel nozzle 51, thesecondary air nozzle 52, and the tertiary air nozzle 53 which areprovided from the center side of the combustion burner, and is equippedwith a flame stabilizer 161. The flame stabilizer 161 is formed in aso-called double cross split structure in which first flame stabilizingmembers 162 and 163 following the horizontal direction and second flamestabilizing members (not illustrated) following the vertical directionare disposed in a cross shape. Then, the first flame stabilizing members162 and 163 are formed in a plate shape with a predetermined thickness.Furthermore, the respective second flame stabilizing members also havethe same structure.

In the embodiment, the outer surfaces of the respective flamestabilizing members 162 and 163 in the flame stabilizer 161 serve as therectification members.

Accordingly, since the fuel gas is divided by the flame stabilizer 161at the opening portion 51 a of the fuel nozzle 51, the inner flamestabilization of the combustion flame may be performed by the fuel gasgoing round to the front end surface side of the flame stabilizer, thetemperature of the outer peripheral portion of the combustion flameunder a high oxygen atmosphere becomes low by the secondary air, and theNOx production amount in the outer peripheral portion of the combustionflame is reduced. Further, at this time, since the fuel gas flowingbetween the fuel nozzle 51 and the flame stabilizer 161 is rectified bythe outer surface of the flame stabilizer 161, the separation of thefuel gas disappears. Further, the flow velocity of the fuel gas flowingtherethrough becomes uniform, and the flow velocity thereof is reduced.Thus, the flame stabilizer 161 may ensure a sufficient flamestabilization ability at the front end portion thereof.

Furthermore, in the above-described respective embodiments, theconfigurations of the respective flame stabilizers have been describedby various examples, but the configuration is not limited to theabove-described configuration. That is, the burner of the invention isused to realize the inner flame stabilization. Then, the flamestabilizer may be provided near the axis of the fuel nozzle instead ofthe inner wall surface of the fuel nozzle, the number or the position ofthe flame stabilizing members may be appropriately set, and the flamestabilizing member may be separated from the inner wall surface of thefuel nozzle. Further, the configuration of the rectification member hasbeen described by various examples, but the configuration is not limitedto the above-described configuration. That is, the rectification membermay be provided between the inner wall surface of the fuel nozzle andthe flame stabilizer. In a case where plural flame stabilizers areprovided, the rectification member may be provided between the flamestabilizers.

Further, in the above-described respective embodiments, as thecombustion device 12, four combustion burners 21, 22, 23, 24, and 25respectively provided in the wall surface of the furnace 11 are disposedas a five stages in the vertical direction, but the configuration is notlimited thereto. That is, the combustion burner may be disposed at thecorner instead of the wall surface. Further, the combustion device isnot limited to the turning combustion type, and may be a frontcombustion type in which the combustion burner is disposed in one wallsurface or an opposed combustion type in which the combustion burnersare disposed in two wall surfaces so as to be opposed to each other.

Further, the flame stabilizer of the invention is equipped with thewidened portion having a triangular cross-sectional shape, but the shapeis not limited thereto. That is, the shape may be a square shape or thewidened portion may not be provided.

Seventh Embodiment

As the combustion burner of the conventional pulverized-coal-combustionboiler, for example, the combustion burner disclosed in PatentLiterature 1 is known. In the combustion device disclosed in PatentLiterature 1, the flame stabilizer is provided between the center insidethe pulverized coal ejecting hole (the primary passage) and the outerperipheral portion, and thus the pulverized coal condensed flow is madeto collide with the flame stabilizer. Thus, the low NOx combustion maybe stably performed in a wide load range.

However, in the conventional combustion device, when the combustion gasobtained by mixing the pulverized coal and the air collides with theflame stabilizer, the separation of the flow occurs at the rear endportion of the flame stabilizer, and hence it is difficult tosufficiently exhibit the flame stabilization ability at the front endportion of the flame stabilizer. Thus, there is a problem in which NOxis produced by the ignition occurring at the outside of the flamestabilizer.

The invention is made to solve the above-described problems, and it isan object of the invention to provide a combustion burner capable ofreducing a NOx production amount by realizing an appropriate flow of afuel gas obtained by mixing solid fuel and air.

FIG. 16 is a front view illustrating a combustion burner according to aseventh embodiment of the invention, FIG. 17 is a cross-sectional viewillustrating the combustion burner of the seventh embodiment, FIG. 18 isa schematic configuration diagram illustrating apulverized-coal-combustion boiler that employs the combustion burner ofthe seventh embodiment, and FIG. 19 is a plan view illustrating thecombustion burner of the pulverized-coal-combustion boiler of theseventh embodiment.

The pulverized-coal-combustion boiler that employs the combustion burnerof the seventh embodiment is a boiler which burns pulverized coal by thecombustion burner using pulverized coal obtained by milling coal as thesolid fuel and collects heat generated by the combustion.

In the seventh embodiment, as illustrated in FIG. 18, apulverized-coal-combustion boiler 210 is the conventional boiler, andincludes a furnace 211 and a combustion device 212. The furnace 211 isformed in a hollow square cylindrical shape and is provided in thevertical direction, and the combustion device 212 is provided in thelower portion of the furnace wall forming the furnace 211.

The combustion device 212 includes plural combustion burners 221, 222,223, 224, and 225 which are attached to the furnace wall. In theembodiment, the combustion burners 221, 222, 223, 224, and 225 aredisposed as one set in the circumferential direction at four equalintervals therebetween, and five sets, that is, five stages are disposedin the vertical direction.

Then, the respective combustion burners 221, 222, 223, 224, and 225 areconnected to coal pulverizers (mills) 231, 232, 233, 234, and 235through pulverized coal supply pipes 226, 227, 228, 229, and 230.Although not illustrated in the drawings, the coal pulverizers 231, 232,233, 234, and 235 have a configuration in which milling tables aresupported in a rotational driving state with rotation axes along thevertical direction inside a housing and plural milling rollers areprovided while facing the upper sides of the milling tables and aresupported so as to be rotatable along with the rotation of the millingtables. Accordingly, when coal is input between plural milling rollersand plural milling tables, the coal is milled into a predetermined sizetherein. Thus, pulverized coal which is classified by transportation air(primary air) may be supplied from pulverized coal supply pipes 226,227, 228, 229, and 230 to the combustion burners 221, 222, 223, 224, and225.

Further, in the furnace 211, wind boxes 236 are provided at theattachment positions of the respective combustion burners 221, 222, 223,224, and 225, where one end portion of an air duct 237 is connected tothe wind box 236 and an air blower 238 is attached to the other endportion of the air duct 237. Accordingly, combustion air (secondary airand tertiary air) sent by the air blower 238 may be supplied from theair duct 237 to the wind box 236, and may be supplied from the wind box236 to each of the respective combustion burners 221, 222, 223, 224, and225.

For this reason, in the combustion device 212, the respective combustionburners 221, 222, 223, 224, and 225 may blow the pulverized fuel-airmixture (fuel gas) obtained by mixing the pulverized coal and theprimary air into the furnace 211 and may blow the secondary air into thefurnace 211. Then, a flame may be formed by igniting the pulverizedfuel-air mixture through an ignition torch (not illustrated).

Furthermore, when generally activating the boiler, the respectivecombustion burners 221, 222, 223, 224, and 225 form a flame by ejectingoil fuel into the furnace 211.

A flue gas duct 240 is connected to the upper portion of the furnace211, and the flue gas duct 240 is equipped with superheaters 241 and242, repeaters 243 and 244, and economizers 245, 246, and 247 asconvection heat transfer portions for collecting the heat of the fluegas. Accordingly, a heat exchange is performed between water and a fluegas that is produced by the combustion in the furnace 211.

The downstream side of the flue gas duct 240 is connected with a fluegas pipe 248 into which the flue gas subjected to heat exchange isdischarged. An air heater 249 is provided between the flue gas pipe 248and the air duct 237, and a heat exchange is performed between the airflowing through the air duct 237 and the flue gas flowing through theflue gas pipe 248, so that the combustion air flowing through thecombustion burners 221, 222, 223, 224, and 225 may increase intemperature.

Furthermore, although not illustrated in the drawings, the flue gas pipe248 is equipped with a denitration device, an electronic precipitator,an inducing air blower, and a desulfurization device, and the downstreamend portion thereof is equipped with a stack.

Accordingly, when the coal pulverizers 231, 232, 233, 234, and 235 aredriven, pulverized coal produced therein is supplied along with thetransportation air to the combustion burners 221, 222, 223, 224, and 225through pulverized coal supply pipes 226, 227, 228, 229, and 230.Further, the heated combustion air is supplied from the air duct 237 tothe respective combustion burners 221, 222, 223, 224, and 225 throughthe wind boxes 236. Then, the combustion burners 221, 222, 223, 224, and225 blow the pulverized fuel-air mixture obtained by mixing thepulverized coal and the transportation air to the furnace 211, blow thecombustion air to the furnace 211, and ignite the pulverized fuel-airmixture and the air at this time so as to form a flame. In the furnace211, when the flame is generated by the combustion of the pulverizedfuel-air mixture and the combustion air and the flame is generated atthe lower portion inside the furnace 211, the combustion gas (the fluegas) rises inside the furnace 211 so as to be discharged to the flue gasduct 240.

Furthermore, the inside of the furnace 211 is maintained at thereduction atmosphere in a manner such that the air supply amount withrespect to the pulverized coal supply amount becomes smaller than thetheoretical air amount. Then, when NOx produced by the combustion of thepulverized coal is reduced in the furnace 211 and additional air isadditionally supplied thereto, the oxidization combustion of thepulverized coal is completed and hence the production amount of NOxcaused by the combustion of the pulverized coal is reduced.

At this time, water supplied from a water feeding pump (not illustrated)is preheated by the economizers 245, 246, and 247, is supplied to asteam drum (not illustrated), and is heated while being supplied torespective water pipes (not illustrated) of the furnace wall so as tobecome saturated steam. Then, the saturated steam is transported to asteam drum (not illustrated). Further, the saturated steam of a steamdrum (not illustrated) is introduced into the superheaters 241 and 242and is superheated by the combustion gas. The superheated steam producedby the superheaters 241 and 242 is supplied to a power generation plant(not illustrated) (for example, a turbine or the like). Further, thesteam which is extracted during the expanding process in the turbine isintroduced into the repeaters 243 and 244, is superheated again, and isreturned to the turbine. Furthermore, the furnace 211 of a drum type(steam drum) has been described, but the invention is not limited to thestructure.

Subsequently, a harmful substance such as NOx is removed from the fluegas which passes through the economizers 245, 246, and 247 of the fluegas duct 240 by a catalyst in the flue gas pipe 248, a particulatesubstance is removed therefrom by the electronic precipitator, and asulfur content is removed therefrom by the desulfurization device. Then,the flue gas is discharged to the atmosphere through the stack.

Here, the combustion device 212 will be described in detail, but sincethe respective combustion burners 221, 222, 223, 224, and 225constituting the combustion device 212 have substantially the sameconfiguration, only the combustion burner 221 that is positioned at theuppermost stage will be described.

As illustrated in FIG. 19, the combustion burner 221 includes thecombustion burners 221 a, 221 b, 221 c, and 221 d which are provided atfour wall surfaces of the furnace 211. The respective combustion burners221 a, 221 b, 221 c, and 221 d are connected with respective branchpipes 226 a, 226 b, 226 c, and 226 d which are branched from apulverized coal supply pipe 226, and are connected with respectivebranch pipes 237 a, 237 b, 237 c, and 237 d branched from the air duct237.

Accordingly, the respective combustion burners 221 a, 221 b, 221 c, and221 d which are positioned at the respective wall surfaces of thefurnace 211 blow the pulverized fuel-air mixture obtained by mixing thepulverized coal and the transportation air to the furnace 211 and blowthe combustion air to the outside of the pulverized fuel-air mixture.Then, the pulverized fuel-air mixture is ignited from the respectivecombustion burners 221 a, 221 b, 221 c, and 221 d, so that four flamesF1, F2, F3, and F4 may be formed. The flames F1, F2, F3, and F4 become aflame swirl flow that turns in the counter-clockwise direction whenviewed from the upside of the furnace 211 (in FIG. 19).

As illustrated in FIGS. 16 and 17, in the combustion burner 221 (221 a,221 b, 221 c, and 221 d) with such a configuration, the combustionburner is equipped with a fuel nozzle 251, a secondary air nozzle 252,and a tertiary air nozzle 253 which are provided from the center sidethereof and is equipped with a flame stabilizer 254. The fuel nozzle 251may blow the fuel gas (the pulverized fuel-air mixture) obtained bymixing the pulverized coal (the solid fuel) with the transportation air(the primary air). The secondary air nozzle 252 is disposed at theoutside of the first nozzle 251 and may blow the combustion air (thesecondary air) to the outer peripheral side of the fuel gas ejected fromthe fuel nozzle 251. The tertiary air nozzle 253 is disposed at theoutside of the secondary air nozzle 252 and may blow the tertiary air tothe outer peripheral side of the secondary air ejected from thesecondary air nozzle 252.

Further, the flame stabilizer 254 is disposed inside the fuel nozzle 51so as to be positioned at the downstream side of the fuel gas blowingdirection and near the axis center, and serves to ignite and stabilizethe fuel gas. The flame stabilizer 254 is formed in a so-called doublecross split structure in which first flame stabilizing members 261 and262 following the horizontal direction and second flame stabilizingmembers 263 and 264 following the vertical direction (the up and downdirection) are disposed in a cross shape. Then, the respective firstflame stabilizing members 261 and 262 include flat portions 261 a and262 a each formed in a flat plate shape having a uniform thickness andwidened portions 61 b and 262 b integrally formed with the front endportions of the flat portions 261 a and 262 a (the downstream endportions in the fuel gas flowing direction). Each cross-section of thewidened portions 261 b and 262 b is formed in an isosceles triangularshape, each width of the widened portions is widened toward thedownstream side in the fuel gas flowing direction, and each front endthereof is formed as a plane perpendicular to the fuel gas flowingdirection. Furthermore, although not illustrated in the drawings, therespective second flame stabilizing members 263 and 264 also have thesame structure.

For this reason, each of the fuel nozzle 251 and the secondary airnozzle 252 has an elongated tubular shape, the fuel nozzle 251 includesa rectangular opening portion 251 a, and the secondary air nozzle 252includes a rectangular annular opening portion 252 a. Thus, the fuelnozzle 251 and the secondary air nozzle 252 are formed as a double tubestructure. The tertiary air nozzle 253 is disposed as a double tubestructure at the outside of the fuel nozzle 251 and the secondary airnozzle 252, and includes a rectangular annular opening portion 253 a. Asa result, the opening portion 252 a of the secondary air nozzle 252 isdisposed at the outside of the opening portion 251 a of the fuel nozzle251, and the opening portion 253 a of the tertiary air nozzle 253 isdisposed at the outside of the opening portion 252 a of the secondaryair nozzle 252. Furthermore, the tertiary air nozzle 253 may not bedisposed as a double tube structure, and the tertiary air nozzle may beobtained by separately disposing plural nozzles at the outer peripheralside of the secondary air nozzle 252.

In the nozzles 251, 252, and 253, the opening portions 251 a, 252 a, and253 a are disposed so as to be flush with one another. Further, theflame stabilizer 254 is supported by the inner wall surface of the fuelnozzle 251 or a plate member (not illustrated) from the upstream side ofthe passage through which the fuel gas flows. Further, since pluralflame stabilizing members 261, 262, 263, and 264 are disposed as theflame stabilizer 254 inside the fuel nozzle 251, the fuel gas passage isdivided into nine segments. Then, in the flame stabilizer 254, thewidened portions 261 b and 262 b of which the widths are wide arepositioned at the front end portions thereof, and the front end surfacesof the widened portions 261 b and 262 b are evenly disposed so as to beflush with the opening portion 251 a.

Further, in the combustion burner 221 of the seventh embodiment, a guidemember 255 is provided so as to guide the fuel gas flowing through thefuel nozzle 251 toward the axis center side. The guide member 255 guidesthe fuel gas in a direction in which the fuel gas is separated from thesecondary air blowing from the secondary air nozzle 252.

The guide member 255 is disposed in the inner wall surface of the frontend portion of the fuel nozzle 251 in the circumferential direction.That is, the guide member 255 includes an upper guide member 265 that isdisposed along the upper wall surface of the fuel nozzle 251, a lowerguide member 266 that is disposed along the lower wall surface of thefuel nozzle 251, and left and right guide members 267 and 268 that aredisposed along the left and right wall surfaces of the fuel nozzle 251.Then, the guide member 255 is disposed at the front end portion of thefuel nozzle 251 so as to face the widened portions 261 b and 262 b ofthe flame stabilizer 254. Then, the guide member 255 is provided with aninclined surface 269 of which the cross-section is formed in atriangular shape and the width is widened toward the downstream side inthe fuel gas flowing direction, the front end thereof is formed as aplane perpendicular to the fuel gas flowing direction. Then, theinclined surface is flush with the opening portions 251 a and 252 a.Furthermore, the guide member 55 is formed by notching a positionintersecting the respective flame stabilizing members 261, 262, 263, and264.

Accordingly, in the combustion burner 221, the fuel gas obtained bymixing the pulverized coal with the primary air blows from the openingportion 251 a of the fuel nozzle 251 into the furnace, the secondary airat the outside thereof blows from the opening portion 252 a of thesecondary air nozzle 252 into the furnace, and the tertiary air at theoutside thereof blows from the opening portion 253 a of the tertiary airnozzle 253 into the furnace. At this time, the fuel gas is divided bythe flame stabilizer 254 at the opening portion 251 a of the fuel nozzle251, and is ignited so as to become the combustion gas. Further, sincethe secondary air blows to the outer periphery of the fuel gas, thecombustion of the fuel gas is promoted. Further, since the tertiary airblows to the outer periphery of the combustion flame, the combustion maybe optimally performed by adjusting the ratio between the secondary airand the tertiary air.

Then, since the flame stabilizer 254 is formed in a split shape in thecombustion burner 221, the fuel gas is divided by the flame stabilizer254 at the opening portion 251 a of the fuel nozzle 251. At this time,the flame stabilizer 254 is disposed at the center zone of the openingportion 251 a of the fuel nozzle 251, and the fuel gas is ignited andstabilized at the center zone. Thus, the inner flame stabilization (theflame stabilization at the center zone of the opening portion 251 a ofthe fuel nozzle 251) of the combustion flame is realized.

For this reason, compared to the configuration in which the outer flamestabilization of the combustion flame is performed, the temperature ofthe outer peripheral portion of the combustion flame becomes low, andhence the temperature of the outer peripheral portion of the combustionflame under the high oxygen atmosphere by the secondary air may becomelow. Thus, the NOx production amount at the outer peripheral portion ofthe combustion flame is reduced.

Further, since the combustion burner 221 employs a configuration inwhich the inner flame stabilization is performed, it is desirable tosupply the fuel gas and the combustion air (the secondary air and thetertiary air) as a straight flow. That is, it is desirable that the fuelnozzle 251 have a structure in which the secondary air nozzle 252 andthe tertiary air nozzle 253 supply the fuel gas, the secondary air, andthe tertiary air as a straight flow instead of a swirl flow. Since thefuel gas, the secondary air, and the tertiary air are ejected as thestraight flow so as to form the combustion flame, the circulation of thegas inside the combustion flame is suppressed in the configuration inwhich the inner flame stabilization of the combustion flame isperformed. Accordingly, the outer peripheral portion of the combustionflame is maintained in a low temperature, and the NOx production amountcaused by the mixture with the secondary air is reduced.

Further, in the combustion burner 221, since the guide member 255 isdisposed so as to be positioned in the entire circumference of the frontend portion of the fuel nozzle 251, the fuel gas flowing through thefuel nozzle 251 is guided toward the center side thereof, that is, theflame stabilizer 254 by the inclined surface 269 of the guide member255. Then, the fuel gas blowing into the furnace by the fuel nozzle 251is guided in a direction in which the fuel gas is separated from thesecondary air blowing from the secondary air nozzle 252. For thisreason, since the fuel gas is separated from the secondary air of whichthe speed is faster than that of the fuel gas, the inner flamestabilization is appropriately performed by the flame stabilizer 254.Further, since the fuel gas is separated from the secondary air and theNOx production amount caused by the mixture with the secondary air isreduced in the fuel gas. Furthermore, the pulverized coal may beappropriately supplied toward the flame stabilizer 254.

In this way, in the combustion burner of the seventh embodiment, thereare provided the fuel nozzle 251 which may blow the fuel gas obtained bymixing the pulverized coal with the primary air and the secondary airnozzle 252 which may blow the secondary air from the outside of the fuelnozzle 251. Also, the flame stabilizer 254 is provided at the front endportion of the fuel nozzle 251 so as to be near the axis center, and theguide member 255 is provided so as to guide the fuel gas flowing throughthe fuel nozzle 251 toward the axis center side.

Accordingly, the fuel gas flowing through the fuel nozzle 251 is guidedtoward the axis center side of the fuel nozzle 251, that is, the flamestabilizer 254 by the guide member 255, and the appropriate flow of thefuel gas inside the fuel nozzle 251 may be realized. As a result, theinner flame stabilization performance using the flame stabilizer 254 maybe improved.

Further, in the combustion burner of the seventh embodiment, the guidemember 255 guides the fuel gas in a direction in which the fuel gas isseparated from the secondary air blowing from the secondary air nozzle252. Accordingly, the fuel gas is guided by the guide member 255 in adirection in which the fuel gas is separated from the secondary air andthe mixing of the fuel gas and the secondary air is suppressed, theinner flame stabilization performance using the flame stabilizer 254 maybe improved, and the outer peripheral portion of the combustion flame ismaintained at the low temperature. Thus, the NOx production amountcaused by the mixing of the combustion gas and the secondary air may bereduced.

Further, in the combustion burner of the seventh embodiment, the guidemember 255 is disposed along the inner wall surface of the fuel nozzle251. Accordingly, the fuel gas flowing through the fuel nozzle 251 maybe effectively guided to the flame stabilizer 254 throughout the entirearea of the fuel nozzle 251, and the fuel gas may be guided in adirection in which the fuel gas is separated from the secondary air. Theinner flame stabilization performance using the flame stabilizer 254 maybe improved.

Further, in the combustion burner of the seventh embodiment, the guidemember 255 is disposed at the front end portion of the fuel nozzle 251so as to face the flame stabilizer 254. In this case, the guide member255 is disposed in the flame stabilizer 254 so as to face the widenedportions 261 b and 262 b. Accordingly, since the fuel gas is guidedtoward the widened portions 261 b and 262 b of the flame stabilizer 254by the guide member 255, the sufficient flame stabilizing function maybe ensured, and the inner flame stabilization performance may beimproved.

Eighth Embodiment

FIG. 20 is a cross-sectional view illustrating a combustion burneraccording to an eighth embodiment of the invention. Furthermore, thesame reference sign will be given to the component having the samefunction as that of the above-described embodiment, and the detaileddescription thereof will not be repeated.

In the combustion burner of the eighth embodiment, as illustrated inFIG. 20, the combustion burner 221 is equipped with the fuel nozzle 251,the secondary air nozzle 252, and the tertiary air nozzle 253 which areprovided from the center side of the combustion burner, and is equippedwith the flame stabilizer 254. Then, since the fuel gas flowing throughthe fuel nozzle 251 is guided to the axis center side, a guide member271 is provided so as to guide the fuel gas in a direction in which thefuel gas is separated from the secondary air blowing from the secondaryair nozzle 252.

The guide member 271 is disposed in the inner wall surface of the fuelnozzle 251 along the circumferential direction so as to be positioned ata position where the guide member does not face the flame stabilizer 254disposed inside the fuel nozzle 251, that is, the upstream side of theflame stabilizer 254 in the fuel gas flowing direction. The guide member271 is formed in the inner wall surface of the fuel nozzle 251 in anannular shape which protrudes toward the flame stabilizer 254, and isequipped with a guide surface (an inclined surface or a curved surface)272 which guides the fuel gas inside the fuel nozzle 251 toward the axiscenter side.

Accordingly, since the guide member 271 is disposed so as to bepositioned at the entire circumference of the front end portion of thefuel nozzle 251 in the combustion burner 221, the fuel gas flowingthrough the fuel nozzle 251 is guided toward the axis center side of thefuel nozzle, that is, the flame stabilizer 254 by the guide surface 272of the guide member 271. Then, the fuel gas flowing from the fuel nozzle251 into the furnace is guided in a direction in which the fuel gas isseparated from the secondary air blowing from the secondary air nozzle252. For this reason, since the fuel gas is separated from the secondaryair of which the speed is faster than that of the fuel gas, the innerflame stabilization using the flame stabilizer 254 may be performed.Further, since the fuel gas is separated from the secondary air and theNOx production amount caused by the mixture with the secondary air isreduced in the fuel gas.

In this way, in the combustion burner of the eighth embodiment, thereare provided the fuel nozzle 251 which may blow the fuel gas obtained bymixing the pulverized coal with the primary air and the secondary airnozzle 252 which may blow the secondary air from the outside of the fuelnozzle 251. Also, the flame stabilizer 254 is provided at the front endportion of the fuel nozzle 251 so as to be near the axis center, and theguide member 271 which guides the fuel gas flowing through the fuelnozzle 251 toward the axis center side is provided at the upstream sideof the flame stabilizer 254 in the fuel gas flowing direction.

Accordingly, the fuel gas flowing through the fuel nozzle 251 is guidedtoward the axis center side of the fuel nozzle 251, that is, the flamestabilizer 254 by the guide member 271, and the appropriate flow of thefuel gas inside the fuel nozzle 251 may be realized. As a result, theinner flame stabilization performance using the flame stabilizer 254 maybe improved. Further, since the guide member 271 is provided at theupstream side in relation to the flame stabilizer 254, the fuel gas maybe effectively guide to the flame stabilizer 254, and the inner flamestabilization performance using the flame stabilizer 254 may beimproved. Further, since the guide member 271 is not provided at thefront end side inside the fuel nozzle 251, the guide member 271 does notserve as the flame stabilizer.

Ninth Embodiment

FIG. 21 is a front view illustrating a combustion burner according to aninth embodiment of the invention. Furthermore, the same reference signwill be given to the component having the same function as that of theabove-described embodiment, and the detailed description thereof willnot be repeated.

In the combustion burner of the ninth embodiment, as illustrated in FIG.21, the combustion burner 221 is equipped with the fuel nozzle 251, thesecondary air nozzle 252, and the tertiary air nozzle 253 which areprovided from the center side of the combustion burner, and is equippedwith the flame stabilizer 254. Then, since the fuel gas flowing throughthe fuel nozzle 251 is guided toward the axis center side of the fuelnozzle, a guide member is provided so as to guide the fuel gas in adirection in which the fuel gas is separated from the secondary airblowing from the secondary air nozzle 252.

The guide member is disposed at the widened portions 261 b and 262 b ofthe flame stabilizer 254 so as to face the inner wall surface of thefuel nozzle 251. That is, in the flame stabilizer 254, the first flamestabilizing members 261 and 262 following the horizontal direction andthe second flame stabilizing members 263 and 264 following the verticaldirection are disposed so as to intersect one another, and the guidemember is formed as notched surfaces 261 c, 262 c, 263 c, and 264 cformed in the end portions of the widened portions 261 b and 262 b ofthe respective flame stabilizing members 261, 262, 263, and 264. Therespective notched surfaces 261 c, 262 c, 263 c, and 264 c are formed ina tapered shape in which an inclined surface is formed at both sides ofeach end portion when viewed from the front sides of the respectiveflame stabilizing members 261, 262, 263, and 264.

Accordingly, in the combustion burner 221, since the notched surfaces261 c, 262 c, 263 c, and 264 c are formed as the guide member at the endportions of the respective flame stabilizing members 261, 262, 263, and264 of the flame stabilizer 254, the fuel gas flowing through the fuelnozzle 251 is guided by the respective notched surfaces 261 c, 262 c,263 c, and 264 c toward the axis center side of the fuel nozzle, thatis, the inside of the respective flame stabilizing members 261, 262,263, and 264 in the longitudinal direction. That is, when the fuel gaspasses through the vicinity of the notched surfaces 261 c, 262 c, 263 c,and 264 c of the respective flame stabilizing members 261, 262, 263, and264, the front end surface sides of the respective flame stabilizingmembers 261, 262, 263, and 264 have a negative pressure. Accordingly,the fuel gas is guided to the negative pressure zone, and hence the flowindicated by the arrow of FIG. 21 occurs.

Then, the fuel gas blowing into the furnace by the fuel nozzle 251 isguided in a direction in which the fuel gas is separated from thesecondary air blowing from the secondary air nozzle 252. For thisreason, since the fuel gas is separated from the secondary air of whichthe speed is faster than that of the fuel gas, the inner flamestabilization using the flame stabilizer 254 may be performed. Further,since the fuel gas is separated from the secondary air and the NOxproduction amount caused by the mixture with the secondary air isreduced in the fuel gas.

In this way, in the combustion burner of the ninth embodiment, there areprovided the fuel nozzle 251 which may blow the fuel gas obtained bymixing the pulverized coal with the primary air and the secondary airnozzle 252 which may blow the secondary air from the outside of the fuelnozzle 251. Also, the flame stabilizer 254 is provided at the front endportion of the fuel nozzle 251 so as to be near the axis center, and asthe guide member that guides the fuel gas flowing through the fuelnozzle 251 toward the axis center side of the fuel nozzle, the notchedsurfaces 261 c, 262 c, 263 c, and 264 c are provided at the end portionsof the respective flame stabilizing members 261, 262, 263, and 264 ofthe flame stabilizer 254.

Accordingly, the fuel gas flowing through the fuel nozzle 251 is guidedby the notched surfaces 261 c, 262 c, 263 c, and 264 c toward the axiscenter side of the fuel nozzle 251, that is, the center side of theflame stabilizer 254, and hence the appropriate flow of the fuel gasinside the fuel nozzle 251 may be realized. As a result, the inner flamestabilization performance using the flame stabilizer 254 may beimproved. Further, since the guide member is formed by forming thenotched surfaces 261 c, 262 c, 263 c, and 264 c at the end portion ofthe flame stabilizer 254, the apparatus may be simplified.

Furthermore, in the ninth embodiment, the guide member is formed as thenotched surfaces 261 c, 262 c, 263 c, and 264 c which are formed at theend portions of the flame stabilizing members 261, 262, 263, and 264 inthe longitudinal direction so as to have a tapered shape, but theinvention is not limited to the shape. For example, the notched surfacesmay be formed by notching only one side of the end portions of the flamestabilizing members 261, 262, 263, and 264 in the longitudinal directionor the notched portions may be formed by cutting the flame stabilizingmembers 261, 262, 263, and 264 in a direction perpendicular to thelongitudinal direction thereof so as to be separated from the inner wallsurface of the fuel nozzle 251. Further, the respective notched surfaces261 c, 262 c, 263 c, and 264 c may be formed in a shape in which thewidths thereof are widened at the downstream side in the fuel gasflowing direction as in the widened portions 261 b and 262 b.

Tenth Embodiment

FIG. 22 is a front view illustrating a combustion burner according to atenth embodiment of the invention. Furthermore, the same reference signwill be given to the component having the same function as that of theabove-described embodiment, and the detailed description thereof willnot be repeated.

In the combustion burner of the tenth embodiment, as illustrated in FIG.22, the combustion burner 221 is equipped with the fuel nozzle 251, thesecondary air nozzle 252, and the tertiary air nozzle 253 which areprovided from the center side of the combustion burner, and is equippedwith the flame stabilizer 254. Then, since the fuel gas flowing throughthe fuel nozzle 251 is guided toward the axis center side of the fuelnozzle, a guide member is provided so as to guide the fuel gas in adirection in which the fuel gas is separated from the secondary airblowing from the secondary air nozzle 252.

The guide member is disposed as triangular plates 281, 282, 283, and 284so as to be positioned at a position where the first flame stabilizingmembers 261 and 262 intersect the second flame stabilizing members 263and 264. Specifically, the guide member is disposed at the outside ofthe position where the widened portions 261 b and 262 b of the firstflame stabilizing members 261 and 262 intersect the widened portions(not illustrated) of the second flame stabilizing members 263 and 264,that is, the opposite side to the axis center of the fuel nozzle 251.The respective triangular plates 281, 282, 283, and 284 are formed in atriangular shape by forming an inclined surface at the outside of eachintersected corner when viewed from the front sides of the respectiveflame stabilizing members 261, 262, 263, and 264.

Accordingly, since the triangular plates 281, 282, 283, and 284 aredisposed at the outside of the intersection points of the respectiveflame stabilizing members 261, 262, 263, and 264 of the flame stabilizer54 in the combustion burner 221, the fuel gas flowing through the fuelnozzle 251 is guided by the respective triangular plates 281, 282, 283,and 284 toward the axis center side of the fuel nozzle, that is, thecenter portions of the respective flame stabilizing members 261, 262,263, and 264. That is, when the fuel gas passes through the vicinity ofthe respective triangular plates 281, 282, 283, and 284, the frontsurface sides of the respective triangular plates 281, 282, 283, and 284have a negative pressure. Accordingly, the fuel gas is guided to thenegative pressure zone, and hence the flow indicated by the arrow ofFIG. 22 occurs.

Then, the fuel gas blowing into the furnace by the fuel nozzle 251 isguided in a direction in which the fuel gas is separated from thesecondary air blowing from the secondary air nozzle 252. For thisreason, since the fuel gas is separated from the secondary air of whichthe speed is faster than that of the fuel gas, the inner flamestabilization using the flame stabilizer 254 may be performed. Further,since the fuel gas is separated from the secondary air and the NOxproduction amount caused by the mixture with the secondary air isreduced in the fuel gas.

In this way, in the combustion burner of the tenth embodiment, there areprovided the fuel nozzle 251 which may blow the fuel gas obtained bymixing the pulverized coal with the primary air and the secondary airnozzle 252 which may blow the secondary air from the outside of the fuelnozzle 251. Also, the flame stabilizer 254 is provided at the front endportion of the fuel nozzle 251 so as to be near the axis center, and asthe guide member that guides the fuel gas flowing through the fuelnozzle 251 toward the axis center side of the fuel nozzle, thetriangular plates 281, 282, 283, and 284 are disposed at theintersection positions of the respective flame stabilizing members 261,262, 263, and 264 of the flame stabilizer 254.

Accordingly, the fuel gas flowing through the fuel nozzle 251 is guidedby the triangular plates 281, 282, 283, and 284 toward the axis centerside of the fuel nozzle 251, that is, the center side the flamestabilizer 254, and hence the appropriate flow of the fuel gas insidethe fuel nozzle 251 may be realized. As a result, the inner flamestabilization performance using the flame stabilizer 254 may beimproved. Further, the flame stabilizer 254 is formed in a structure inwhich two first flame stabilizing members 261 and 262 provided in thehorizontal direction while being parallel to each other in the verticaldirection with a predetermined gap therebetween and two second flamestabilizing members 263 and 264 provided in the vertical direction whilebeing parallel to each other in the horizontal direction with apredetermined gap therebetween are disposed so as to intersect oneanother. Accordingly, since the flame stabilizer 254 is formed in adouble cross structure, the sufficient flame stabilizing function may beensured. Further, since the guide member is formed as the triangularplates 281, 282, 283, and 284, the fuel gas flowing through the fuelnozzle 251 may be effectively guided toward the axis center side.

Furthermore, in the tenth embodiment, the guide member is formed as thetriangular plates 281, 282, 283, and 284, but the invention is notlimited to the shape. For example, the respective triangular plates 281,282, 283, and 284 may be formed in a shape in which the widths thereofat the downstream side in the fuel gas flowing direction are widened asin the widened portions 261 b and 262 b.

Eleventh Embodiment

FIG. 23 is a cross-sectional view illustrating a combustion burneraccording to an eleventh embodiment of the invention, and FIG. 24 is across-sectional view illustrating a modified example of the combustionburner of the eleventh embodiment. Furthermore, the same reference signwill be given to the component having the same function as that of theabove-described embodiment, and the detailed description thereof willnot be repeated.

In the combustion burner of the eleventh embodiment, as illustrated inFIG. 23, the combustion burner 221 is equipped with the fuel nozzle 251,the secondary air nozzle 252, and the tertiary air nozzle 253 which areprovided from the center side of the combustion burner, and is equippedwith a flame stabilizer 291. Then, since the fuel gas flowing throughthe fuel nozzle 251 is guided toward the axis center side of the fuelnozzle, a guide member is provided so as to guide the fuel gas in adirection in which the fuel gas is separated from the secondary airblowing from the secondary air nozzle 252.

That is, the flame stabilizer 291 includes flame stabilizing members 292and 293 following the horizontal direction, and the flame stabilizingmembers 292 and 293 include flat portions 292 a and 293 a which areformed in a flat plate shape having a uniform thickness and widenedportions 292 b and 293 b which are integrally formed with the front endportions of the flat portions 292 a and 293 a (the downstream endportions in the fuel gas flowing direction). Each cross-section of thewidened portions 292 b and 293 b is formed in an isosceles triangularshape, each width of the widened portions is widened toward thedownstream side in the fuel gas flowing direction, and each front endthereof is formed as a plane perpendicular to the fuel gas flowingdirection.

Then, the guide member is formed by directing the front end portions ofthe flame stabilizing members 292 and 293 toward the axis center side ofthe fuel nozzle 251. That is, the flame stabilizing members 292 and 293are inclined with respect to the axis center of the fuel nozzle 251 in amanner such that the widened portions 292 b and 293 b formed at thefront end portion thereof are disposed so as to be close to each othercompared to the rear end portions of the flat portions 292 a and 293 a.

Accordingly, since the front end portions of the flame stabilizingmembers 292 and 293 are disposed so as to be close to each other at theflame stabilizer 291 inside the fuel nozzle 251 in the combustion burner221, the fuel gas flowing through the fuel nozzle 251 is guided by theflame stabilizing members 292 and 293 toward the axis center side. Thatis, since the front end portions of the flame stabilizing members 292and 293 are close to each other, the fuel gas becomes fast between theflame stabilizing members 292 and 293 and becomes low between the fuelnozzle 251 and the flame stabilizing members 292 and 293. Thus, the fuelgas is guided toward the axis center of the fuel nozzle 251 on thewhole.

Then, the fuel gas blowing into the furnace by the fuel nozzle 251 isguided in a direction in which the fuel gas is separated from thesecondary air blowing from the secondary air nozzle 252. For thisreason, since the fuel gas is separated from the secondary air of whichthe speed is faster than that of the fuel gas, the inner flamestabilization using the flame stabilizer 291 is appropriately performed.Further, since the fuel gas is separated from the secondary air and theNOx production amount caused by the mixture with the secondary air isreduced in the fuel gas.

In this case, the inclination angles of the flame stabilizing members292 and 293 constituting the flame stabilizer 291 may be adjusted. Thatis, as illustrated in FIG. 24, the flame stabilizing members 292 and 293are supported so as to be rotatable up and down by support shafts 295and 296 following the horizontal direction perpendicular to the fuel gasflowing direction of the fuel nozzle 251, and are rotatable by a drivingdevice 297. That is, the inclination angles of the flame stabilizingmembers 292 and 293 may be individually adjusted by the driving device297.

Accordingly, the optimal blowing state of the fuel gas may be maintainedin a manner such that the driving device 297 individually adjusts theangles of the flame stabilizing members 292 and 293 based on, forexample, the characteristics or the speed of the fuel gas, the speed ofthe secondary air, and the combustion state inside the furnace 211.

In this way, in the combustion burner of the eleventh embodiment, thereare provided the fuel nozzle 251 which may blow the fuel gas obtained bymixing the pulverized coal with the primary air and the secondary airnozzle 252 which may blow the secondary air from the outside of the fuelnozzle 251. Also, the flame stabilizer 291 is provided at the front endportion of the fuel nozzle 251 so as to be near the axis center, and asthe guide member that guides the fuel gas flowing through the fuelnozzle 251 toward the axis center side of the fuel nozzle, the flamestabilizing members 292 and 293 of the flame stabilizer 291 are disposedso that the front end portions thereof face the axis center side of thefuel nozzle 251.

Accordingly, the fuel gas flowing through the fuel nozzle 251 is guidedby the inclined flame stabilizing members 292 and 293 toward the axiscenter side of the fuel nozzle 251, that is, the center side of theflame stabilizer 291, and hence the appropriate flow of the fuel gasinside the fuel nozzle 251 may be realized. As a result, the inner flamestabilization performance using the flame stabilizer 291 may beimproved. Further, since the guide member is formed by the arrangementof the flame stabilizing members 292 and 293 of the flame stabilizer291, the structure may be simplified.

Further, in the combustion burner of the eleventh embodiment, it ispossible to individually adjust the inclination angles of the flamestabilizing members 292 and 293 by the driving device 297. Accordingly,the optimal blowing state of the fuel gas may be maintained by changingthe angles of the flame stabilizing members 292 and 293 based on, forexample, the characteristics or the speed of the fuel gas, the speed ofthe secondary air, and the combustion state inside the furnace 211.

Furthermore, in the above-described respective embodiments, theconfigurations of the flame stabilizers 254 and 291 have been describedby various examples, but the invention is not limited to theabove-described configurations. That is, the burner of the invention isused to realize the inner flame stabilization. Then, the flamestabilizer may be provided toward the axis center side of the fuelnozzle 251 instead of the inner wall surface of the fuel nozzle 251, thenumber or the position of the flame stabilizing members may beappropriately set, and the flame stabilizing member may be separatedfrom the inner wall surface of the fuel nozzle 251. Further, theconfiguration of the guide member has been described by variousexamples, but the configuration is not limited to the above-describedconfiguration. That is, the fuel gas inside the fuel nozzle may beguided toward the axis center side by the guide member.

Further, the flame stabilizer of the invention is equipped with thewidened portion having a triangular cross-sectional shape, but theinvention is not limited to the shape. That is, the shape may be asquare shape and the widened portion may not be provided.

Further, in the above-described respective embodiments, the guide memberof the invention is provided in the inner wall surface of the fuelnozzle or the flame stabilizer, but a separate member may be providedbetween the inner wall surface of the fuel nozzle and the flamestabilizer. For example, the guide member may be formed in a square orargyle frame shape by providing the guide member between the inner wallsurface of the fuel nozzle and the flame stabilizer in a directionparallel to or intersecting the flame stabilizer.

Further, in the above-described respective embodiments, four combustionburners 221, 222, 223, 224, and 225 provided in the wall surface of thefurnace 211 are disposed at five stages in the vertical direction as thecombustion device 212, but the invention is not limited to theconfiguration. That is, the combustion burner may be disposed at thecorner instead of the wall surface. Further, the combustion device isnot limited to the turning combustion type, but may be a frontcombustion type in which the combustion burner is disposed in one wallsurface or an opposed combustion type in which the combustion burnersare disposed in two wall surfaces so as to be opposed to each other.

Twelfth Embodiment

Hitherto, as the solid-fuel-combustion boiler, there is known, forexample, a pulverized-coal-combustion boiler which burns pulverized coal(coal) as solid fuel. In such a pulverized-coal-combustion boiler, twokinds of combustion types, the turning combustion boiler and thewall-combustion boiler are known.

Among these, in the pulverized-coal-combustion turning combustionboiler, secondary air input ports for inputting the secondary air areprovided at the upper and lower sides of the primary air input from thecoal-combustion burner (the solid-fuel-combustion burner) along withpulverized coal as fuel so as to adjust the flow rate of the secondaryair around the coal-combustion burner. Since the air amount of theprimary air is needed to transport the pulverized coal as fuel, the airamount is defined in the roller milling device that obtains thepulverized coal by milling coal. Then, since the secondary air blows bythe amount necessary for forming the entire flame inside the turningcombustion boiler, the secondary air amount of the turning combustionboiler is substantially obtained by subtracting the primary air amountfrom the entire air amount necessary for the combustion of thepulverized coal. Further, in the burner of the turning combustionboiler, the outer flame stabilization is performed which strengths theignition of the outer periphery of the flame by the separation of thepulverized coal according to the lean and rich levels.

On the contrary, in the burner of the opposed wall-fired boiler, forexample, as disclosed in Patent Literature 2, the secondary air and thetertiary air are introduced to the outer peripheral side of the primaryair (the supply of the pulverized coal) so as to finely adjust the airintroduction amount. That is, generally, a burner with an outer flamestabilization structure is provided in which a flame stabilizingmechanism (for a front end angle adjustment operation, a turningoperation, or the like) is provided at the outer periphery of the burnerformed in a circular shape when viewed from the inside of the furnaceand an input port for the secondary air or the tertiary air isconcentrically provided so as to be near the outer periphery of theburner.

Further, in the conventional pulverized-coal-combustion burner, forexample, as disclosed in Patent Literature 3, the ignition of the outerperiphery of the flame is further strengthened by the separation of thepulverized coal to the outer periphery according to the lean and richlevels. Further, even in Patent Literature 4, the outer peripheral flamestabilizer and the flame stabilizer formed in a split structure aredisclosed. In this case, the outer peripheral flame stabilizer is usedfor a primary function and the split structure is used for a secondaryfunction.

Incidentally, in the conventional turning combustion boiler, since thesecondary air input ports for inputting the secondary air arerespectively integrally formed at the upper and lower sides of thecoal-combustion burner, the amount of the secondary air input from thesecondary air input port may not be finely adjusted. For this reason, ahot oxygen remaining zone is formed at the outer periphery of the flame.Thus, the hot oxygen remaining zone is particularly wide in a zone wherethe secondary air concentrates, and hence the NOx production amountincreases.

Further, in the conventional coal-combustion burner, generally, theouter periphery of the burner is equipped with the flame stabilizingmechanism (for a front end angle adjustment operation, a turningoperation, or the like), and a port for inputting the secondary air (orthe tertiary air) is provided near the outer periphery. For this reason,the ignition occurs at the outer periphery of the flame, so that a largeamount of oxygen is mixed with the outer periphery of the flame. As aresult, the combustion at the outer periphery of the flame occurs in astate where the oxygen concentration in the hot oxygen remaining zone ofthe outer periphery of the flame is high, so that NOx is produced at theouter periphery of the flame. In this way, the NOx produced in the hotoxygen remaining zone of the outer periphery of the flame passes throughthe outer periphery of the flame, the reduction is later than that ofthe inside of the flame, which causes NOx from the coal-combustionboiler.

Meanwhile, even in the opposed wall-fired boiler, since the ignitionoccurs at the outer periphery of the flame by the swirl, NOx is producedas in the outer periphery of the flame.

Due to these circumstances, in the solid-fuel-combustion burner and thesolid-fuel-combustion boiler that burns the pulverized solid fuel as inthe conventional coal-combustion burner and the conventionalcoal-combustion boiler, it is desirable to reduce the finally NOxproduction amount of NOx discharged from the additional air input unitby suppressing the hot oxygen remaining zone formed at the outerperiphery of the flame.

The invention is made in view of the above-described circumstances, andit is an object of the invention to provide a solid-fuel-combustionburner and a solid-fuel-combustion boiler capable of reducing a finalNOx production amount of NOx discharged from an additional air inputunit by suppressing (weakening) a hot oxygen remaining zone formed in anouter periphery of a flame.

Hereinafter, one embodiment of the solid-fuel-combustion burner and thesolid-fuel-combustion boiler according to the invention will bedescribed by referring to the drawings. Furthermore, in the embodiment,a turning combustion boiler with a solid-fuel-combustion burner thatuses pulverized coal (coal as pulverized solid fuel) will be describedas an example of the solid-fuel-combustion burner and thesolid-fuel-combustion boiler, but the invention is not limited thereto.

A turning combustion boiler 310 illustrated in FIGS. 27 to 29 inputs airinto a furnace 311 in plural stages so as to set a zone from a burner312 to an additional air input unit (hereinafter, referred to as a “AApart”) 314 as a reduction atmosphere, whereby the NOx of the flue gasdecreases.

The reference sign 320 of the drawings indicates a solid-fuel-combustionburner that inputs the pulverized coal (the pulverized solid fuel) andthe air, and the reference sign 315 indicates an additional air inputnozzle that ejects additional air. For example, as illustrated in FIG.27, the solid-fuel-combustion burner 320 is connected with a pulverizedcoal fuel-air mixture transportation pipe 316 that transports thepulverized coal by the primary air and an air blowing duct 317 thatsupplies the secondary air, and the additional air input nozzle 315 isconnected with the air blowing duct 317 that supplies the secondary air.

In this way, the turning combustion boiler 310 employs a turningcombustion type in which the solid-fuel-combustion burner 320 forinputting the air and the pulverized coal (coal) of the pulverized fuelinto the furnace 311 is formed as the turning combustion type burner 312disposed at each corner of each stage.

The solid-fuel-combustion burner 320 illustrated in FIG. 25 includes apulverized coal burner (fuel burner) 321 which inputs the pulverizedcoal and the air and secondary air input ports 330 which arerespectively disposed at the upper and lower sides of the pulverizedcoal burner 321.

For example, as illustrated in FIG. 26, each secondary air input port330 includes a damper 340 capable of adjusting an opening degree as aflow rate adjusting unit provided for each of the secondary air supplylines branched from the air blowing duct 317 in order to adjust the airflow amount for each port.

The pulverized coal burner 321 includes a rectangular coal primary port322 which inputs the pulverized coal transported by the primary air anda coal secondary port 323 which is provided so as to surround the coalprimary port 322 and inputs a part of the secondary air. Furthermore, asillustrated in FIG. 26, the coal secondary port 323 also includes adamper 340 capable of adjusting an opening degree as a flow rateadjusting unit. Furthermore, the coal primary port 322 may have acircular shape or an oval shape.

Split members 324 are disposed in a plurality of directions at the frontside of the passage of the pulverized coal burner 321, that is, thefront side of the passage of the coal primary port 322, and are fixed bysupport members (not illustrated). For example, as illustrated in FIG.25(a), two split members 324 are disposed in a lattice shape with apredetermined gap therebetween so that one split member is positioned ineach of the up and down direction and the left and right direction atthe outlet opening portion of the coal primary port 322.

That is, two split members 324 are formed in a cross type in a mannersuch that the split members are disposed in two different directions ofthe up and down direction and the left and right direction. Here, theoutlet opening portion of the coal primary port 322 of the pulverizedcoal burner 321 is finely divided (divided into four segments), but thenumber of the split members 324 may be plural numbers in each of the upand down direction and the left and right direction.

Further, a pressure loss is large in a portion sandwiched by the splitmembers 324, and the flow velocity of the ejection port decreases, sothat the inner ignition is further promoted.

The split members 324 with such a configuration suppress the hot oxygenremaining zone H formed in the outer periphery of the flame F, andeffectively reduces the final NOx production amount of NOx dischargedfrom the AA part 314.

The split members 324 employ, for example, the cross-sectional shapeillustrated in FIGS. 30(a) to 30(d), and hence smoothly divide the flowof the pulverized coal and the air so that the flow is disturbed.

Each split member 324 illustrated in FIG. 30(a) has a triangularcross-sectional shape. The triangular shape illustrated in the drawingis an equilateral-triangular shape or an isosceles triangular shape, andone outlet-side edge facing the inside of the furnace 311 is disposed soas to intersect the direction in which the pulverized coal and the airflow. In other words, an arrangement is employed in which one cornerforming the triangular cross-section is disposed so as to face thedirection in which the pulverized coal and the air flow.

A split member 324A illustrated in FIG. 30(b) has a substantiallyT-shaped cross-section, and a surface substantially perpendicular to thedirection in which the pulverized coal and the air flow is disposed atthe outlet side facing the inside of the furnace 311. Furthermore, forexample, as illustrated in FIG. 30(c), a split member 324A′ having atrapezoidal cross-sectional shape may be provided by deforming thesubstantially T-shaped cross-section.

Further, a split member 324B illustrated in FIG. 30(d) has asubstantially L-shaped cross-section. That is, in a case where across-section obtained by cutting out a part of the substantial T-shapeis particularly disposed in the left and right (horizontal) direction,when a substantial L-shape is formed by removing an upper convexportion, it is possible to prevent the deposit of the pulverized coal tothe split member 324B. Furthermore, when a lower convex portionincreases in size by the removable amount of the upper convex portion,the separation performance necessary for the split member 324B may beensured.

However, the cross-sectional shape of the split member 324 or the likeis not limited to the example illustrated in the drawings, and may besubstantially formed in, for example, a Y-shape.

In the solid-fuel-combustion burner 320 with such a configuration, thesplit member 324 which is provided near the center of the outlet openingof the pulverized coal burner 321 divides the passage of the pulverizedcoal and the air so as to disturb the flow therein, and forms arecirculation zone at the front side (the downstream side) of the splitmember 324. Thus, the split member serves as an inner flamestabilization mechanism.

In general, the conventional solid-fuel-combustion burner 320 ignitesthe pulverized coal of the fuel by the radiation of the outer peripheryof the flame. When the pulverized coal is ignited by the outer peripheryof the flame, NOx is produced in the hot oxygen remaining zone H (seeFIG. 25(b)) of the outer periphery of the flame where hot oxygenremains, and hence the NOx discharge amount increase while the reductionis not sufficiently performed.

However, since the split member 324 serving as the inner flamestabilization mechanism is provided, the pulverized coal is ignited atthe inside of the flame. For this reason, NOx is produced at the insideof the flame, and the NOx produced at the inside of the flame contains alarge amount of hydrocarbons having a reduction action. For this reason,the reduction is promptly performed inside the flame which does not havesufficient air. Accordingly, the solid-fuel-combustion burner 320 isprovided in a structure in which the flame stabilization performed bythe flame stabilizer at the outer periphery of the flame is stopped,that is, the flame stabilizing mechanism is not provided at the outerperiphery of the burner, and hence the production of NOx at the outerperiphery of the flame may be suppressed.

Particularly, when a cross type is employed in which the split members324 are disposed in a plurality of directions, the intersection portionobtained by intersecting the split members 324 in different directionsmay be easily provided near the center of the outlet opening of thepulverized coal burner 321. When the intersection portion exists nearthe center of the outlet opening of the pulverized coal burner 321, thepassage of the pulverized coal and the air is divided into pluralsegments near the center of the outlet opening of the pulverized coalburner 321, and hence the flow is disturbed when the flow is dividedinto plural flows.

That is, when the split members 324 exist in one direction of the leftand right direction, the dispersion or the ignition of the air at thecenter portion is delayed, so that a zone exists in which air is locallyand extremely insufficient. Thus, the unburned combustible contentincreases. However, in a cross type in which the intersection portion isformed by disposing the split members 324 in a plurality of directions,the mixing of the air at the inside of the flame is promoted and theignition surface is finely divided. As a result, the unburnedcombustible content may be reduced.

In other words, when the split members 324 are disposed so as to formthe intersection portion, the mixing and the dispersion of the air arepromoted to the inside of the flame, so that the ignition surface isfinely divided. Thus, the ignition position exists near the centerportion (the axis center portion) of the flame, and hence the unburnedcombustible content of the pulverized coal is reduced. That is, sinceoxygen easily enters the center portion of the flame, the inner ignitionis effectively performed. Accordingly, the reduction is promptlyperformed at the inside of the flame, and hence the NOx productionamount is reduced.

As a result, it is possible to more easily suppress the production ofNOx at the outer periphery of the flame by using thesolid-fuel-combustion burner 320 that does not have the flame stabilizerat the outer periphery of the flame by stopping the flame stabilizationusing the flame stabilizer provided at the outer periphery of the flame.

In the split members 324 disposed in a plurality of directions, in theembodiment, when the width of the split member 324 viewed from theinside of the furnace is set as the splitter width W, the split membershaving different splitter widths W for the respective directions aredisposed in a cross type.

For example, in configuration example of the cross type illustrated inFIG. 25(a), the outlet opening portion of the coal primary port 322 isequipped with one split member (hereinafter, referred to as a “verticalsplitter”) 324V disposed in the up and down direction and one splitmember (hereinafter, referred to as a “horizontal splitter”) 324Hdisposed in the left and right direction.

Then, the splitter width Wv of the vertical splitter 324V is larger andwider than the splitter width Wh of the horizontal splitter 324H(Wv>Wh), but an inverse configuration may be set.

That is, the split member 324 illustrated in the drawings strengthensthe vertical splitter function, but relatively degrades the horizontalsplitter function. For this reason, a structure is used in which thesplitter width Wv of the vertical splitter 324V is set to be larger thanthe splitter width Wh of the horizontal splitter 324H.

This configuration is prepared to handle a change in the angle of thefuel burner 321 of which the angle may be changed.

For example, as illustrated in FIG. 25(b), the fuel burner 321 mayappropriately change the burner angle (the nozzle angle) α in the up anddown direction so as to adjust the temperature of the steam produced bythe turning combustion boiler 310 to a desired value.

However, even when the burner angle α changes, the angle of the splitmember 324 that is fixed and supported to an appropriate position doesnot change while being interlocked with the fuel burner 321. For thisreason, the positional relation between the fuel burner 321 and thesplit member 324 changes in response to a change in the burner angle α.

When the burner angle α changes in the up and down direction, thepositional relation between the pulverized coal flow and the horizontalsplitter 324H changes when inputting the pulverized coal and the primaryair. Since a change in the positional relation is largely influenced asthe splitter width Wh of the horizontal splitter 324H increases, theburner performance is eventually influenced, and hence it is difficultto uniformly maintain the burner performance. Accordingly, it isdesirable to prevent the burner performance from being influenced evenwhen the burner angle α of the fuel burner 321 changes.

Therefore, in the embodiment, the split member 324 that strengthens thevertical splitter function by relatively increasing the splitter widthWv of the vertical splitter 324V may narrow the splitter width Wh of thehorizontal splitter 324H to the minimally necessary width, and hencesuppress a change in the positional relation caused by a change in theburner angle α to the minimal value.

Accordingly, since the split member 324 is formed in a cross type inwhich the splitters exist in both directions of the up and downdirection and the left and right direction by remaining the horizontalsplitter 324H having a small splitter width W, it is possible tomaintain a state where the mixing of the air is promoted and theignition surface is finely divided. For this reason, in the split member324, the air may easily enter the center portion of the flame. As aresult, it is possible to minimally suppress a change in the positionalrelation caused by a change in the burner angle α while keeping theadvantage of the cross type in which the unburned combustible contentmay be reduced by the promotion of the ignition of the center portion,and to substantially uniformly maintain the burner performance.

Further, in a case of the turning combustion type in which the secondaryair input port 330 is disposed in the up and down direction of thepulverized coal burner 321, the splitter width Wh of the horizontalsplitter 324H is set to be larger and wider than the splitter width Wvof the vertical splitter 324V (Wh>Wv).

This is because the splitter function is strengthened when the splitterwidth Wv of the vertical splitter 324V is larger than the necessaryvalue and the splitter easily becomes the ignition source of thepulverized coal.

Moreover, regarding the ignition in the vicinity of both upper and lowerend portions of the vertical splitter 324V, since the ignition source isclose to the secondary air input port 330, the ignition at the outerperiphery of the flame easily and directly interferes with the secondaryair. As a result, a large amount of air is mixed with the pulverizedcoal that is ignited at the outer periphery of the flame using thevertical splitter 324V as the ignition source. Accordingly, NOx isproduced at the hot oxygen remaining zone H of the outer periphery ofthe flame where hot oxygen remains. The NOx remains without sufficientreduction, and increases the final NOx discharge amount.

However, when the splitter width Wh of the horizontal splitter 324H isset to a large width so as to strengthen the splitter function of thehorizontal splitter 324H, the ignition source in the vicinity of thesecondary air input port 330 existing at the upper and lower sides ofthe pulverized coal burner 321 decreases in size. That is, thedownstream side of the wide horizontal splitter 324H is equipped with anegative pressure zone as a large recirculation zone, and hence a strongsplitter function is exhibited. For this reason, the flow of thepulverized coal and the primary air may easily concentrate on the centerportion in the up and down direction.

As a result, the ignition occurs at the outer periphery of the flame byusing the vicinity of both end portions of the vertical splitter 324V asthe ignition source, and the amount of the pulverized coal mixed with alarge amount of air largely decreases. Meanwhile, the mixing and thedispersion of the pulverized coal and the primary air are promoted tothe inside of the flame, so that the air (oxygen) may easily enter thecenter portion of the flame. As a result, since the inner ignition iseffectively performed, the prompt reduction occurs at the inside of theflame, and hence the NOx production amount is reduced.

In this case, since the cross type split members 324 exist in the up anddown direction and the left and right direction by leaving the verticalsplitter 324V, that is, forming the vertical splitter 324V with thesmall splitter width Wv, the mixing of the air is promoted and theignition surface is finely divided. For this reason, in thesolid-fuel-combustion burner 320 with the cross type split members 324,the air may easily enter the center portion of the flame, and hence theunburned combustible content may be reduced by the promotion of theignition of the center portion.

Thirteenth Embodiment

Next, a solid-fuel-combustion burner according to a thirteenthembodiment of the invention will be described.

In the embodiment, the split members 324 provided in thesolid-fuel-combustion burner 320 are formed as the split members 324that are disposed in a plurality of directions and having differentsplitter widths W. Furthermore, the splitter width W of the centerportion of three or more split members disposed in the same direction isset to a large width, and the widths of the peripheral portions arerelatively narrowed.

In the split members 324 with such a configuration, since the splitterwith a large width is disposed at the center portion of thesolid-fuel-combustion burner 320, the splitter function of the centerportion is strengthened, and hence the inner ignition may bestrengthened while preventing the outer ignition.

That is, since the solid-fuel-combustion burner 320 of the embodimentincludes the cross type split members 324 of which the center portionhas a large width, the existence of the splitter serving as the ignitionsource at the outer peripheral portion of the pulverized coal burner 321is suppressed as minimal as possible, so that the outer ignition may beprevented or suppressed. Further, since the splitter function of thecenter portion is strengthened, the air easily enters the center portionof the flame. As a result, the unburned combustible content may bereduced by the promotion of the ignition of the center portion.

Incidentally, in the above-described configuration example, threesplitters are disposed in each of the up and down direction and the leftand right direction, and only one splitter disposed at the centerportion in the up and down direction and the left and right directionhas a large width. However, not only the number of the splitters butalso the number or the position of the wide splitter is not limited tothe invention.

For example, a configuration may be employed in which four splitters aredisposed in the up and down direction and the left and right directionand two splitters disposed at the center portions in the up and downdirection and the left and right direction have a large width. Further,both splitters disposed at the center portions in the up and downdirection and the left and right direction do not have a large width.For example, only the splitter member disposed at the center portion inthe up and down direction or the left and right direction may have alarge width. Accordingly, a configuration is also included in whichthree or more splitters are disposed in one of a plurality of directionsso as to have a large width at the center portion and one splitterhaving a wide width or a narrow width or one splitter having a narrowwidth is disposed in the other direction.

Fourteenth Embodiment

Next, a solid-fuel-combustion burner according to a fourteenthembodiment of the invention will be described by referring to FIG. 31.Furthermore, the same reference sign will be given to the same componentas that of the above-described embodiment, and the repetitivedescription thereof will not be repeated. In the embodiment, the splitmembers 324 that are provided in the solid-fuel-combustion burner 320Aso as to guide the flow of the pulverized coal and the primary air tothe inside of the center portion of the flame (the axis center side)include a shielding member that is attached to the intersection cornerbetween the splitters disposed in a plurality of directions. That is, inorder to strengthen the inner flame stabilization or to increase theignition surface of the inside of the flame by further improving thefunction of the split members 324, the shielding member that reduces thepassage sectional area is provided in at least one position of theintersection corner formed by intersecting the split members 324 as thefunction strengthening member of the split members 324.

As the shielding member, for example, a triangular plate 350 isdesirable which is attached to the split members 324 so as to block theintersection center portion side of the intersection corner. Then, theopening area of the coal primary port 322 viewed from the inside of thefurnace, that is, the passage sectional area of the pulverized coal andthe primary air decreases by the amount corresponding to the area of thetriangular plate 350. The triangular plate 350 decreases the passagesectional area of the pulverized coal and the primary air, and increasesthe ignition surface of the inside of the flame. Also, the triangularplate has a function of guiding the flow of the pulverized coal and theprimary air toward the center portion.

In other words, the triangular plate 350 is a shielding member that isformed at the downstream side of the split member 324 so as to increasea negative pressure zone as a recirculation zone, and may strengthen theflame stabilization effect of the split member 324.

Accordingly, the shielding member may be provided in at least oneposition of four intersection corners formed at the intersectionportions of the splitters 324H and 324V intersecting each other in theup and down direction and the left and right direction.

Further, the shielding member is not limited to the triangular plate(the triangular plate member) 350 illustrated in FIG. 32(a). Forexample, a plate member may be formed with a shape formed by ¼ of thecircular or oval shape. Moreover, for example, as in a triangularpyramid 350A illustrated in FIG. 32(b), an inclined surface may beprovided so as to guide a flow outward and form a recirculation zone.

In this way, when the shielding member such as the triangular plate 350or the triangular pyramid 350A is provided at the intersection portionsof the splitters 324H and 324V, the function of the split member 324 isfurther improved. Accordingly, the ignition surface of the inside of theflame may be increased or the inner flame stabilization may bestrengthened.

According to the solid-fuel-combustion burner and thesolid-fuel-combustion boiler of the above-described embodiments, it ispossible to reduce the final NOx production amount of NOx dischargedfrom the AA part 314 by suppressing the hot oxygen remaining zone Hformed at the outer periphery of the flame F.

Furthermore, the invention is not limited to the above-describedembodiments. For example, the pulverized solid fuel is not limited tothe pulverized coal, and may be appropriately modified without departingfrom the spirit of the invention.

Fifteenth Embodiment

Incidentally, in the conventional coal-combustion burner, generally, theouter periphery of the burner is equipped with the flame stabilizingmechanism (for a front end angle adjustment operation, a turningoperation, or the like), and the secondary air (or tertiary air) inputport is provided near the outer periphery. For this reason, the ignitionoccurs at the outer periphery of the flame, and hence a large amount ofair is mixed at the outer periphery of the flame. As a result, thecombustion at the outer periphery of the flame occurs at a hightemperature state in which the oxygen concentration at the hot oxygenremaining zone of the outer periphery of the flame is high. Accordingly,NOx is produced at the outer periphery of the flame. In this way, sincethe NOx produced at the hot oxygen remaining zone of the outer peripheryof the flame passes through the outer periphery of the flame, thereduction is later than that of the inside of the flame, which causesthe production of the NOx from the coal-combustion boiler.

Meanwhile, even in the opposed wall-fired boiler, the ignition occurs atthe outer periphery of the flame by the swirl, and hence NOx is producedas in the outer periphery of the flame.

Due to these circumstances, in the solid-fuel-combustion burner and thesolid-fuel-combustion boiler that burns the pulverized solid fuel as inthe conventional coal-combustion burner and the conventionalcoal-combustion boiler, it is desirable to reduce the final NOxproduction amount of NOx discharged from the additional air input unitby suppressing the hot oxygen remaining zone formed at the outerperiphery of the flame.

The invention is made in view of the above-described circumstance, andit is an object of the invention to provide a solid-fuel-combustionburner and a solid-fuel-combustion boiler capable of reducing a finalNOx production amount of NOx discharged from an additional air inputunit by suppressing (weakening) the hot oxygen remaining zone formed atthe outer periphery of the flame.

Hereinafter, one embodiment of the solid-fuel-combustion burner and thesolid-fuel-combustion boiler according to the invention will bedescribed by referring to the drawings. Furthermore, in the embodiment,a turning combustion boiler with a solid-fuel-combustion burner usingpulverized coal (coal as pulverized solid fuel) as fuel will bedescribed as an example of the solid-fuel-combustion burner and thesolid-fuel-combustion boiler, but the invention is not limited thereto.

A turning combustion boiler 410 illustrated in FIGS. 35 to 37 inputs airinto the furnace 411 in plural stages so that the zone from the burner412 to the additional air input unit (hereinafter, referred to as an “AApart”) 414 becomes a reduction atmosphere. In this way, NOx in the fluegas may be decreased.

The reference sign 420 of the drawings indicate a solid-fuel-combustionburner that inputs pulverized coal (pulverized solid fuel) and air, andthe reference sign 415 indicates an additional air input nozzle thatinputs additional air. For example, as illustrated in FIG. 35, thesolid-fuel-combustion burner 420 is connected with a pulverized coalfuel-air mixture transportation pipe 416 that transports the pulverizedcoal by the primary air and an air blowing duct 417 that supplies thesecondary air, and an additional air input nozzle 415 is connected withthe air blowing duct 417 that supplies the secondary air.

In this way, the turning combustion boiler 410 employs a turningcombustion type in which the solid-fuel-combustion burner 420 thatinputs the air and the pulverized coal (coal) of the pulverized fuelinto the furnace 411 is formed as the turning combustion type burner 412that is disposed at each corner of each stage and one or plural swirlflames are generated at each stage.

The solid-fuel-combustion burner 420 illustrated in FIG. 33 includes apulverized coal burner (fuel burner) 421 that inputs the pulverized coaland the air and a coal secondary port that ejects the secondary air fromthe outer periphery of the pulverized coal burner 421. In theembodiment, the secondary air port that ejects the secondary air fromthe outer periphery of the pulverized coal burner 421 includes secondaryair input ports 430 respectively disposed at the upper and lower sidesof the pulverized coal burner 421 and a coal secondary port 423.

For example, as illustrated in FIG. 34, in order to adjust the air flowrate for each port, the secondary air input port 430 includes a damper440 which is provided as a flow rate adjusting unit for each secondaryair supply line branched from the air blowing duct 417 so as to adjustthe opening degree thereof.

The pulverized coal burner 421 includes a rectangular coal primary port422 which inputs the pulverized coal transported by the primary air anda coal secondary port 423 which is provided so as to surround the coalprimary port 422 and inputs a part of the secondary air. Furthermore, asillustrated in FIG. 34, even the coal secondary port 423 includes thedamper 440 as the flow rate adjusting unit capable of adjusting theopening degree. Furthermore, the coal primary port 422 may be formed ina circular or oval shape.

A split member 424 is disposed at the front side of the passage of thepulverized coal burner 421, that is, the front side of the passage ofthe coal primary port 422, and is fixed by a support member (notillustrated). For example, as illustrated in FIG. 33(a), one splitmember 424 is disposed in the horizontal direction so as to besubstantially positioned at the center position in the up and downdirection at the outlet opening portion of the coal primary port 422,and both end portions thereof in the horizontal (left and right)direction are partially removed so as to be formed as removing portions424 a. Furthermore, in FIG. 33(a), the removing portions 424 a aredepicted by a dashed line.

In this case, as illustrated in FIG. 33, when the passage width of thepulverized coal burner 421, that is, the passage width (the passagewidth from the axis center) of the coal primary port 422 is denoted byL1, the length (the length from the axis center) L2 of the split member424 obtained by removing a part of the end portion adjacent to the coalsecondary port 423 from the split member 424 is set so that thedimensional ratio L2/L1 satisfies the in equation of L2/L1>0.2. Further,the dimension ratio L2/L1 more desirably satisfies the in equation ofL2/L1>0.6. That is, it is desirable to form the removing portion 424 awhich is formed by removing a part of the end portion from the splitmember 424 so that the dimension ratio satisfies the condition ofL2/L1>0.2. Then, it is more desirable to form the removing portion tosatisfy the condition of L2/L1>0.6.

The split member 424 employs, for example, the cross-sectional shapeillustrated in FIGS. 38(a) to 38(d), and may smoothly divide the flow ofthe pulverized coal and the air so as to be disturbed.

The split member 424 illustrated in FIG. 38(a) has a triangularcross-sectional shape. The triangular shape illustrated in the drawingsis an equilateral-triangular or isosceles triangle, and the outlet sideedge facing the inside of the furnace 411 is disposed so as to besubstantially perpendicular to the direction in which the pulverizedcoal and the air flow. In other words, an arrangement is employed inwhich one corner forming the triangular cross-section faces thedirection in which the pulverized coal and the air flow.

A split member 424A illustrated in FIG. 38(b) has a substantiallyT-shaped cross-section, and a surface substantially perpendicular to thedirection in which the pulverized coal and the air flow is disposed atthe outlet side facing the inside of the furnace 411. Furthermore, forexample, as illustrated in FIG. 38(c), a split member 424A′ having atrapezoidal cross-sectional shape may be formed by deforming thesubstantially T-shaped cross-section.

A split member 424B illustrated in FIG. 38(d) has a substantiallyL-shaped cross-section. That is, in a case where a cross-sectionobtained by cutting out a part of the substantial T-shape isparticularly disposed in the left and right (horizontal) direction, whena substantial L-shape is formed by removing an upper convex portion, itis possible to prevent the deposit of the pulverized coal to the splitmember 424B. Furthermore, when a lower convex portion increases in sizeby the removable amount of the upper convex portion, the separationperformance necessary for the split member 424B may be ensured.

However, the cross-sectional shape of the split member 424 or the likeis not limited to the example illustrated in the drawings, and may besubstantially formed in, for example, a Y-shape.

Incidentally, the split member 424 of the embodiment is not limitedthereto. Accordingly, the split member 424 may have, for example, aconfiguration in which four split members are disposed in total in alattice shape so that two split members are disposed in each of the upand down direction and the left and right direction. In this case, thetwo split members disposed in the up and down direction are provided sothat both upper and lower end portions near the secondary air input port430 are removed. Then, the two split members disposed in the left andright direction may be provided so as to reach both left and right endportions of the coal primary port 422. Likewise, various configurationsmay be selected.

That is, when four split members 424 are provided, the split members aredisposed in a cross type so that the split members are disposed in alattice shape in two different directions of the up and down directionand the left and right direction, so that the outlet opening portion ofthe coal primary port 422 of the pulverized coal burner 421 is finelydivided (into nine segments). Further, a pressure loss is large in aportion sandwiched by the split members 424, and the flow velocity ofthe ejection port decreases, so that the inner ignition is furtherpromoted.

Furthermore, for example, regarding the up and down direction of thesplit member 424, the removal portion (the removing portion 424 a) maynot be positioned to the split member 424 in the left and rightdirection. Further, since the end portion of the split member 424 maysuppress the ignition at the outer peripheral portion by the removal atthe front side thereof, a structure is desirable in which the outerperiphery is not equipped with the flame stabilizer.

Further, the removing portion 424 a may be provided in a direction inwhich the secondary air amount increases, that is, the secondary airinput port 430 is provided near the outer periphery (the upper and lowersides) of the coal secondary port 423.

In the solid-fuel-combustion burner 420 with such a configuration, thesplit member 424 that is provided near the center of the outlet openingof the pulverized coal burner 421 divides the passage of the pulverizedcoal and the air so as to disturb the flow therein, and forms therecirculation zone at the front side (downstream side) of the splitmember 424. Thus, the split member serves as an inner flamestabilization mechanism.

In general, the conventional solid-fuel-combustion burner 420 ignitesthe pulverized coal of the fuel by the radiation of the outer peripheryof the flame. When the pulverized coal is ignited by the outer peripheryof the flame, NOx is produced in the hot oxygen remaining zone H (seeFIG. 33(b)) of the outer periphery of the flame where hot oxygenremains, and hence the NOx discharge amount increase while the reductionis not sufficiently performed.

However, since the split member 424 serving as the inner flamestabilization mechanism is provided, the pulverized coal is ignited atthe inside of the flame. For this reason, NOx is produced at the insideof the flame, and the NOx produced at the inside of the flame contains alarge amount of hydrocarbons having a reduction action. For this reason,the reduction is promptly performed inside the flame which does not havesufficient air. Accordingly, the solid-fuel-combustion burner 420 isprovided in a structure in which the flame stabilization performed bythe flame stabilizer at the outer periphery of the flame is stopped,that is, the flame stabilizing mechanism is not provided at the outerperiphery of the burner by forming the removing portion 424 a, and hencethe production of NOx at the outer periphery of the flame may besuppressed.

Particularly, when a cross type is employed in which the split members424 are disposed in a plurality of directions, the intersection portionobtained by intersecting the split members 424 in different directionsmay be easily provided near the center of the outlet opening of thepulverized coal burner 421. When the intersection portion exists nearthe center of the outlet opening of the pulverized coal burner 421, thepassage of the pulverized coal and the air is divided into pluralsegments near the center of the outlet opening of the pulverized coalburner 421, and hence the flow is disturbed when the flow is dividedinto plural flows.

That is, when the split members 424 exist in one direction of the leftand right direction, the dispersion or the ignition of the air at thecenter portion is delayed, so that a zone exists in which air is locallyand extremely insufficient. Thus, the unburned combustible contentincreases. However, in a cross type in which the intersection portion isformed by disposing the split members 424 in a plurality of directions,the mixing of the air at the inside of the flame is promoted and theignition surface is finely divided. As a result, the unburnedcombustible content may be reduced.

In other words, when the split members 424 are disposed so as to formthe intersection portion, the mixing and the dispersion of the air arepromoted to the inside of the flame, so that the ignition surface isfinely divided. Thus, the ignition position exists near the centerportion (the axis center portion) of the flame, and hence the unburnedcombustible content of the pulverized coal is reduced. That is, sinceoxygen easily enters the center portion of the flame, the inner ignitionis effectively performed. Accordingly, the reduction is promptlyperformed at the inside of the flame, and hence the NOx productionamount is reduced.

As a result, it is possible to more easily suppress the production ofNOx at the outer periphery of the flame by using thesolid-fuel-combustion burner 420 that does not have the flame stabilizerat the outer periphery of the flame by stopping the flame stabilizationusing the flame stabilizer provided at the outer periphery of the flame.

In the split members 424 disposed in a plurality of directions, in theembodiment, it is desirable to remove a plurality of end portionsadjacent to the coal secondary port 423 at the outer peripheral side ofthe split member 424, that is, at least a part of left and right endportions.

In a first modified example of the configuration example illustrated inFIG. 33(a), as described above, both upper and lower end portions as theouter peripheral side of the split member 424 in the up and downdirection are removed. That is, in the outer peripheral zone formed byremoving both upper and lower end portions of the split member 424, thesplit member 424 does not exist, and the distance from the split member424 to the coal secondary port 423 and the secondary air input port 430increases. Furthermore, in the cross type split member 424, the outerperipheral ignition occurs even at both left and right end portions inthe horizontal direction. However, in the turning combustion, the amountof the secondary air blowing to the periphery of the flame from the leftand right direction is limited. For this reason, in the embodiment, theignition surface is ensured by leaving both left and right end portions.

As a result, in the outer peripheral side zones of both upper and lowerend portions without the split member 424, the ignition using the splitmember 424 as the ignition source does not occur. Meanwhile, at thecenter portion side of the split member 424 as the inside of the flame,the flame stabilizing function may be effectively used. Accordingly, inboth upper and lower end portion side zones that easily and directlyinterfere with the secondary air due to the close distance with respectto the secondary air input port 430 that inputs a large amount of thesecondary air, the ignition does not easily occurs. For this reason, itis possible to prevent or suppress a zone with a high temperature and ahigh oxygen concentration at the outer periphery of the flame. That is,the split member 424 that is obtained by removing both upper and lowerend portions adjacent to the coal secondary port 423 and the secondaryair input port 430 may strengthen the ignition inside the pulverizedcoal burner 420, and prevent a hot oxygen zone at the outer periphery ofthe flame, that is, the hot oxygen zones at the upper and lower ends ofthe flame.

Incidentally, the removal of the end portion of the split member 424 isnot limited to the first modified example.

In a second modified example, two split members 424 are disposed in eachof the up and down direction and the left and right direction. In thiscase, as in the above-described embodiment, both upper and lower endportions near the coal secondary port 423 and the secondary air inputport 430 are removed in the split member 424 in the up and downdirection. The split member 424 may be one or three or more.

In a third modified example, three split members 424 are disposed ineach of the up and down direction and the left and right direction. Inthe split member 424 in the up and down direction of the modifiedexample, both upper and lower end portions near the coal secondary port423 and the secondary air input port 430 of only one split memberdisposed at the center portion is removed. Furthermore, in the splitmember 424 disposed in the up and down direction, that is, the splitmember 424 in the up and down direction of which both upper and lowerend portions are not removed, it is desirable to decrease the ignitionsurface area by further narrowing the splitter widths W of both upperand lower end portions or the entire portion.

In this way, in the solid-fuel-combustion burner 420 for the turningcombustion boiler in which the coal secondary port 423 and the secondaryair input port 430 are disposed near the upper and lower sides of thepulverized coal burner 421, when the cross type split member 424 ofwhich at least a part of both upper and lower end portions are removedis provided, it is possible to prevent or suppress a zone with a hightemperature and a high oxygen concentration from being formedparticularly at the upper and lower end portions easily and directlyinterfering with the secondary air.

When the hot oxygen remaining zone formed at the outer periphery of theflame is suppressed in this way, the NOx produced inside the flamegenerated by the pre-mixture combustion is effectively reduced.Accordingly, it is possible to decrease the NOx amount of NOx finallydischarged from the AA part 414 due to a decrease in the NOx amountreaching the AA part 414 or a decrease in the NOx amount produced by theinput of the additional air.

Further, in a fourth modified example, three or more cross type splitmembers 424 are disposed in at least one of the up and down directionand the left and right direction, and the end portions are removedexcept for at least one split member disposed at the center portion inthe up and down direction and the left and right direction.

That is, in the fourth modified example, the configuration in whichthree split members 424 are disposed in each of the up and downdirection and the left and right direction is the same as those of thesecond modified example and the third modified example. However, in themodified example, one split member 424 disposed at the center portion inthe up and down direction and the left and right direction is providedso as to reach the end portion, and all end portions in the up and downdirection and the left and right direction of the split member 424disposed at both end portions are removed.

In this way, in a case of the split member 424 of the fourth modifiedexample, a structure is formed in which the split member 424 does notexist at the outer peripheral portion except for the center portion inthe up and down direction and the left and right direction, and hencethe split member 424 does not exist in a zone which contributes theouter peripheral combustion the most. For this reason, the split member424 of the configuration example like the fourth modified exampleeffectively prevents the outer peripheral ignition in which the splitmember 424 becomes the ignition source.

Further, for example, like the fifth modified example, in the splitmember 424 of the embodiment, at least a part of both left and right endportions which may become the outer peripheral ignition source may beremoved if necessary.

That is, in the cross type split member 424 serving as the flamestabilizer, the outer peripheral ignition may be generated even at bothleft and right end portions in the horizontal direction. Accordingly,the structure in which all end portions in the up and down direction andthe left and right direction are removed may effectively and completelyprevent the outer ignition. Particularly, when the secondary air inputport is provided at the left and right sides of the pulverized coalburner 421, it is desirable to remove both left and right end portionsso as to reduce the ignition source due to the same reason as that ofthe above-described upper and lower secondary air input ports 430.

Sixteenth Embodiment

Next, a solid-fuel-combustion burner that is applied to a opposedwall-fired boiler according to a sixteenth embodiment of the inventionwill be described.

In the solid-fuel-combustion burner of the embodiment, a plurality ofconcentric secondary air input ports are provided at the outer peripheryof the coal primary port having a circular cross-section. The secondaryair input port is formed as, for example, two stages with an innersecondary air input port and an outer secondary air input port, but theinvention is not limited thereto.

Further, the center portion of the outlet of the coal primary port isequipped with a plurality of split members (for example, four splitmembers disposed in the vertical direction and the horizontal directionin total) that are disposed in a lattice shape in two differentdirections. In this case, the split members may be disposed by thenumber, the arrangement, and the cross-sectional shape described in afifteenth embodiment. However, since the shape is particularly circular,it is desirable to remove the end portion in the entire circumference.Alternatively, a configuration may be employed in which a circular splitmember is provided and plural radial split members are disposed insidethe circular shape so as to divide the circular circumferentialdirection into plural segments. In this case, the circular split membersmay have plural concentric circles.

According to the solid-fuel-combustion burner and thesolid-fuel-combustion boiler of the embodiment, it is possible to reducethe final NOx production amount of NOx discharged from the AA part 414by suppressing the hot oxygen remaining zone H formed at the outerperiphery of the flame.

Furthermore, the invention is not limited to the above-describedembodiments. For example, the pulverized solid fuel is not limited tothe pulverized coal, and may be appropriately modified without departingfrom the spirit of the invention.

Seventeenth Embodiment

In the pulverized-coal-combustion boiler, the pulverized coal (coal) isused as the solid fuel. In this case, the coal contains moisture or avolatile content, and the amount of moisture changes in accordance withthe type thereof. For this reason, there is a need to control theoperation of the boiler in response to the volatile content or themoisture contained in the coal.

As the control of the operation of the boiler in consideration of thevolatile content of the coal, for example, the control disclosed inPatent Literatures above is known. In the pulverized coal burner and theboiler using the same disclosed in Patent Literature 5, there areprovided the pulverized coal fuel-air mixture passage that ejects thepulverized coal fuel-air mixture obtained by mixing the pulverized coalwith the transportation air and the hot gas supply passage that ejects ahot gas with a low oxygen concentration at a high temperature effectivefor the discharge of the volatile content of the pulverized coal.Further, in the coal-combustion boiler disclosed in Patent Literature 6,there are provided a temperature detector that detects the temperatureof the primary air for supplying the pulverized coal to thecoal-combustion boiler, the primary air temperature adjusting unit thatadjusts the temperature of the primary air, and the control device thatcontrols the primary air temperature adjusting unit so that thetemperature of the primary air becomes a predetermined temperature basedon the detection result of the temperature detector.

In the conventional boiler, the entire pulverized coal is heated so asto adjust the moisture or the volatile content, and is burned inside thefurnace. In this case, the operation parameter needs to be adjustedbased on the operation output of the boiler, and it is difficult todirectly set the operation parameter based on the characteristics of thecoal.

The invention is made to solve the above-described problems, and it isan object of the invention to provide a boiler and a method foroperating the boiler capable of improving an operation efficiency byappropriately burning solid fuel and a volatile content contained in thesolid fuel.

FIG. 39 is a schematic configuration diagram illustrating apulverized-coal-combustion boiler as a boiler according to a seventeenthembodiment of the invention, FIG. 40 is a plan view illustrating acombustion burner of the pulverized-coal-combustion boiler of theseventeenth embodiment, FIG. 41 is a front view illustrating thecombustion burner of the seventeenth embodiment, FIG. 42 is across-sectional view illustrating the combustion burner of theseventeenth embodiment, and FIG. 43 is a graph illustrating a NOxproduction amount and an unburned combustible content production amountwith respect to the primary air and the secondary air.

The pulverized-coal-combustion boiler that employs the combustion burnerof the seventeenth embodiment is a boiler capable of collecting the heatgenerated by the combustion by burning the pulverized coal obtained bymilling the coal as the solid fuel and burning the pulverized coalthrough the combustion burner.

In the embodiment, as illustrated in FIG. 39, apulverized-coal-combustion boiler 510 is a conventional boiler, andincludes a furnace 511 and a combustion device 512. The furnace 511 isformed in a hollow square cylindrical shape, and is provided in thevertical direction. Then, the combustion device 512 is provided in thelower portion of the furnace wall forming the furnace 511.

The combustion device 512 includes plural combustion burners 521, 522,523, 524, and 525 which are attached to the furnace wall. In theembodiment, the combustion burners 521, 522, 523, 524, and 525 aredisposed as one set in the circumferential direction at four equalintervals therebetween, and five sets, that is, five stages are disposedin the vertical direction.

Then, the respective combustion burners 521, 522, 523, 524, and 525 areconnected to coal pulverizers (mills) 531, 532, 533, 534, and 535through pulverized coal supply pipes 526, 527, 528, 529, and 530.Although not illustrated in the drawings, the coal pulverizers 531, 532,533, 534, and 535 have a configuration in which milling tables aresupported in a rotational driving state with rotation axes along thevertical direction inside a housing and plural milling rollers areprovided while facing the upper sides of the milling tables and aresupported so as to be rotatable along with the rotation of the millingtables. Accordingly, when coal is input between plural milling rollersand plural milling tables, the coal is milled into a predetermined sizetherein. Thus, pulverized coal which is classified by transportation air(primary air) may be supplied from pulverized coal supply pipes 526,527, 528, 529, and 530 to the combustion burners 521, 522, 523, 524, and525.

Further, in the furnace 511, wind boxes 536 are provided at theattachment positions of the respective combustion burners 521, 522, 523,524, and 525, where one end portion of an air duct 537 is connected tothe wind box 536 and an air blower 538 is attached to the other endportion of the air duct 537. Moreover, in the furnace 511, an additionalair nozzle 539 is provided above the attachment positions of therespective combustion burners 521, 522, 523, 524, and 525, and an endportion of an air duct 540 branched from the air duct 537 is connectedto the additional air nozzle 539. Accordingly, the combustion air (thesecondary air and the tertiary air) sent from the air blower 538 issupplied from the air duct 537 to the wind box 536 so as to be suppliedfrom the wind boxes 36 to the respective combustion burners 521, 522,523, 524, and 525 and to be supplied from the branched air duct 540 tothe additional air nozzle 539.

For this reason, in the combustion device 512, the respective combustionburners 521, 522, 523, 524, and 525 may blow a pulverized fuel-airmixture (fuel gas) obtained by mixing pulverized coal and primary airinto the furnace 511 and may blow secondary air and tertiary air intothe furnace 511. Then, a flame may be formed by igniting the pulverizedfuel-air mixture through an ignition torch (not illustrated).

Further, the pulverized coal supply pipes 526, 527, 528, 529, and 530are equipped with flowrate adjustment valves 541, 542, 543, 544, and 545capable of adjusting the pulverized fuel-air mixture amount, the airduct 537 is equipped with a flowrate adjustment valve 546 capable ofadjusting the amount of the combustion air (the secondary air and thetertiary air), and the branched air duct 540 is equipped with a flowrateadjustment valve 547 capable of adjusting the additional air amount.Then, a control device 548 may adjust the opening degrees of therespective flowrate adjustment valves 541, 542, 543, 544, 545, 546, and547. In this case, the pulverized coal supply pipes 526, 527, 528, 529,and 530 may not be equipped with the flowrate adjustment valves 541,542, 543, 544, and 545.

Furthermore, when generally activating the boiler, the respectivecombustion burners 521, 522, 523, 524, and 525 form a flame by ejectingoil fuel into the furnace 511.

A flue gas duct 550 is connected to the upper portion of the furnace511, and the flue gas duct 550 is equipped with superheaters 551 and552, repeaters 553 and 554, and economizers 555, 556, and 557 asconvection heat transfer portions for collecting the heat of the fluegas. Accordingly, a heat exchange is performed between water and a fluegas that is produced by the combustion in the furnace 511.

The downstream side of the flue gas duct 550 is connected with a fluegas pipe 558 into which the flue gas subjected to the heat exchange isdischarged. An air heater 559 is provided between the flue gas pipe 558and the air duct 557, and a heat exchange is performed between the airflowing through the air duct 537 and the flue gas flowing through theflue gas pipe 558, so that the temperature of the combustion airsupplied to the combustion burners 521, 522, 523, 524, and 525 may beincreased.

Furthermore, although not illustrated in the drawings, the flue gas pipe558 is equipped with a denitration device, an electronic precipitator,an inducing air blower, and a desulfurization device, and the downstreamend portion thereof is equipped with a stack.

Accordingly, when the coal pulverizers 531, 532, 533, 534, and 535 aredriven, pulverized coal produced therein is supplied along with thetransportation air to the combustion burners 521, 522, 523, 524, and 525through the pulverized coal supply pipes 526, 527, 528, 529, and 530.Further, the heated combustion air is supplied from the air duct 537 tothe respective combustion burners 521, 522, 523, 524, and 525 throughthe wind boxes 536, and is supplied from the branched air duct 540 tothe additional air nozzle 539. Then, the combustion burners 521, 522,523, 524, and 525 blow the pulverized fuel-air mixture obtained bymixing the pulverized coal, the transportation air to the furnace 511and blow the combustion air to the furnace 511, and ignite thepulverized fuel-air mixture and the air at this time so as to form aflame. Further, the additional air nozzle 539 may perform the combustioncontrol by blowing the additional air to the furnace 511. In the furnace511, when a flame is generated by the combustion of the pulverizedfuel-air mixture and the combustion air and the flame is generated atthe lower portion inside the furnace 511, the combustion gas (the fluegas) rises inside the furnace 511, and is discharged to the flue gasduct 550.

Furthermore, the inside of the furnace 511 is maintained at thereduction atmosphere in a manner such that the air supply amount withrespect to the pulverized coal supply amount becomes smaller than thetheoretical air amount. Then, when NOx produced by the combustion of thepulverized coal is reduced in the furnace 511 and additional air isadditionally supplied thereto, the oxidization combustion of thepulverized coal is completed and hence the production amount of NOxcaused by the combustion of the pulverized coal is reduced.

At this time, water supplied from a water feeding pump (not illustrated)is preheated by the economizers 555, 556, and 557, is supplied to asteam drum (not illustrated), and heated while being supplied to therespective water pipes (not illustrated) of the furnace wall so as tobecome saturated steam. Then the saturated steam is transported to asteam drum (not illustrated). Further, the saturated steam of the steamdrum (not illustrated) is introduced into the superheaters 551 and 552and is superheated by the combustion gas. The superheated steam producedby the superheaters 551 and 552 is supplied to a power generation plant(not illustrated) (for example, a turbine or the like). Further, thesteam which is extracted during the expanding process in the turbine isintroduced into the repeaters 553 and 554, is superheated again, and isreturned to the turbine. Furthermore, the furnace 511 of a drum type(steam drum) has been described, but the invention is not limited to thestructure.

Subsequently, a harmful substance such as NOx is removed from the fluegas which passes through the economizers 555, 556, and 557 of the fluegas duct 550 by a catalyst of a denitration device (not illustrated) inthe flue gas pipe 558, a particulate substance is removed therefrom bythe electronic precipitator, and a sulfur content is removed therefromby the desulfurization device. Then, the flue gas is discharged to theatmosphere through the stack.

Here, the combustion device 512 will be described in detail, but sincethe respective combustion burners 521, 522, 523, 524, and 525constituting the combustion device 512 have substantially the sameconfiguration, only the combustion burner 521 that is positioned at theuppermost stage will be described.

As illustrated in FIG. 40, the combustion burner 521 includes thecombustion burners 521 a, 521 b, 521 c, and 521 d which are provided atfour wall surfaces of the furnace 511. The respective combustion burners521 a, 521 b, 521 c, and 521 d are connected with respective branchpipes 526 a, 526 b, 526 c, and 526 d which are branched from apulverized coal supply pipe 526, and are connected with respectivebranch pipes 537 a, 537 b, 537 c, and 537 d branched from the air duct537.

Accordingly, the respective combustion burners 521 a, 521 b, 521 c, and521 d which are positioned at the respective wall surfaces of thefurnace 511 blow the pulverized fuel-air mixture obtained by mixing thepulverized coal and the transportation air to the furnace 511 and blowthe combustion air to the outside of the pulverized fuel-air mixture.Then, the pulverized fuel-air mixture is ignited from the respectivecombustion burners 521 a, 521 b, 521 c, and 521 d, so that four flamesF1, F2, F3, and F4 may be formed. The flames F1, F2, F3, and F4 become aflame swirl flow that turns in the counter-clockwise direction whenviewed from the upside of the furnace 511 (in FIG. 40).

As illustrated in FIGS. 41 and 42, in the combustion burner 521 (521 a,521 b, 521 c, 521 d) with such a configuration, the combustion burner isequipped a fuel nozzle 561, a secondary air nozzle 562, and a tertiaryair nozzle 563 from the center side thereof and is equipped with a flamestabilizer 564. The fuel nozzle 561 may blow the fuel gas (thepulverized fuel-air mixture) obtained by mixing the pulverized coal (thesolid fuel) with the transportation air (the primary air). The secondaryair nozzle 562 is disposed at the outside of the first nozzle 561 andmay blow the combustion air (the secondary air) to the outer peripheralside of the fuel gas ejected from the fuel nozzle 561. The tertiary airnozzle 563 is disposed at the outside of the secondary air nozzle 562,and may blow the tertiary air to the outer peripheral side of thesecondary air ejected from the secondary air nozzle 562.

Further, the flame stabilizer 564 is disposed inside the fuel nozzle 561so as to be positioned at the downstream side of the fuel gas blowingdirection and near the axis center, and serves to ignite and stabilizethe fuel gas. The flame stabilizer 564 is formed in a so-called doublecross split structure in which two flame stabilizing members followingthe horizontal direction and two flame stabilizing members following thevertical direction (the up and down direction) are disposed in a crossshape. Then, in the flame stabilizer 564, the widened portions areformed in the front end portions of the respective flame stabilizingmembers (the downstream end portions in the fuel gas flowing direction).

For this reason, each of the fuel nozzle 561 and the secondary airnozzle 562 has an elongated tubular shape, the fuel nozzle 561 includesa rectangular opening portion 561 a, and the secondary air nozzle 562includes a rectangular annular opening portion 562 a. Thus, the fuelnozzle 561 and the secondary air nozzle 562 are formed in a double tubestructure. the tertiary air nozzle 563 is disposed as a double tubestructure at the outside of the fuel nozzle 561 and the secondary airnozzle 562, and includes a rectangular annular opening portion 563 a. Asa result, the opening portion 562 a of the secondary air nozzle 562 isdisposed at the outside of the opening portion 561 a of the fuel nozzle561, and the opening portion 563 a of the tertiary air nozzle 563 isdisposed at the outside of the opening portion 562 a of the secondaryair nozzle 562.

In the nozzles 561, 562, and 563, the opening portions 561 a, 562 a, and563 a are disposed so as to be flush with one another. Further, theflame stabilizer 564 is supported by the inner wall surface of the fuelnozzle 561 or a plate member (not illustrated) from the upstream side ofthe passage through which the fuel gas flows. Further, since pluralflame stabilizing members are disposed as the flame stabilizer 564inside the fuel nozzle 561, the fuel gas passage is divided into ninesegments. Then, in the flame stabilizer 564, the widened portion ofwhich the width is wide is positioned at the front end portion thereof,and the front end surface of the widened portion is disposed so as to beflush with the opening portion 561 a.

Further, in the combustion burner 521, the fuel nozzle 561 is connectedto the pulverized coal supply pipe 526 from the coal pulverizer 531. Thesecondary air nozzle 562 is connected with one connection duct 566branched from the air duct 537 from the air blower 538, and the tertiaryair nozzle 563 is connected with the other connection duct 567 branchedfrom the air duct 537. A flowrate adjustment valve (a three-way valve ora damper) 568 is attached to the branch portions of the respectiveconnection ducts 566 and 567 from the air duct 537. Then, the controldevice 548 (see FIG. 39) may adjust the opening degree of the flowrateadjustment valve 568, and may adjust the distribution of the air to therespective connection ducts 566 and 567.

Accordingly, in the combustion burner 521, the fuel gas obtained bymixing the pulverized coal with the primary air blows from the openingportion 561 a of the fuel nozzle 561 into the furnace, the secondary airblows from the opening portion 562 a of the secondary air nozzle 562 tothe outside thereof, and the tertiary air blows from the opening portion563 a of the tertiary air nozzle 563 to the outside thereof. At thistime, the fuel gas is branched at the opening portion 561 a of the fuelnozzle 561 by the flame stabilizer 564, and is ignited and burned so asto become a fuel gas. Further, since the secondary air blows to theouter periphery of the fuel gas, the combustion of the fuel gas ispromoted. Further, since the tertiary air blows to the outer peripheryof the combustion flame, the outer peripheral portion of the combustionflame is cooled.

Then, since the flame stabilizer 564 is formed in a split shape in thecombustion burner 521, the fuel gas is divided by the flame stabilizer564 at the opening portion 561 a of the fuel nozzle 561. At this time,the flame stabilizer 564 is disposed at the center zone of the openingportion 561 a of the fuel nozzle 561, and the fuel gas is ignited andstabilized at the center zone. Thus, the inner flame stabilization ofthe combustion flame (the flame stabilization at the center zone of theopening portion 561 a of the fuel nozzle 561) is realized.

For this reason, compared to the configuration in which the outer flamestabilization of the combustion flame is performed, the temperature ofthe outer peripheral portion of the combustion flame becomes low, andhence the temperature of the outer peripheral portion of the combustionflame under the high oxygen atmosphere by the secondary air may becomelow. Thus, the NOx production amount at the outer peripheral portion ofthe combustion flame is reduced.

Further, since the combustion burner 521 employs a configuration inwhich the inner flame stabilization is performed, it is desirable tosupply the fuel gas and the combustion air (the secondary air and thetertiary air) as a straight flow. That is, it is desirable that the fuelnozzle 561 have a structure in which the secondary air nozzle 562 andthe tertiary air nozzle 563 supply the fuel gas, the secondary air, andthe tertiary air as a straight flow instead of a swirl flow. Since thefuel gas, the secondary air, and the tertiary air are ejected as thestraight flow so as to form the combustion flame, the circulation of thegas inside the combustion flame is suppressed in the configuration inwhich the inner flame stabilization of the combustion flame isperformed. Accordingly, the outer peripheral portion of the combustionflame is maintained in a low temperature, and the NOx production amountcaused by the mixture with the secondary air is reduced.

Incidentally, in the pulverized-coal-combustion boiler 510 of theembodiment, the pulverized coal (coal) is used as the solid fuel, andthe pulverized coal contains the volatile content. Accordingly, thecombustion state becomes different due to the volatile content.

Therefore, in the pulverized-coal-combustion boiler 510 of theembodiment, as illustrated in FIGS. 39 and 42, since the control device548 may adjust the fuel gas amount, the secondary air amount, thetertiary air amount, and the additional air amount by changing theopening degrees of the respective flowrate adjustment valves 541, 542,543, 544, 545, 546, 547, and 568, the fuel gas amount, the secondary airamount, the tertiary air amount, and the additional air amount areadjusted in response to the volatile content of the pulverized coal.

In this case, it is desirable that the control device 548 adjust thedistribution of the total air amount of the primary air and thesecondary air and the air amount of the additional air in response tothe volatile content of the pulverized coal. Specifically, thedistribution of the total air amount of the primary air and thesecondary air and the total air amount of the tertiary air and theadditional air is adjusted.

In the embodiment, since the primary air amount and the additional airamount are predetermined air amounts, the control device 548 adjusts thedistribution of the secondary air and the tertiary air in response tothe volatile content of the pulverized coal. Then, the control device548 increases the distribution of the secondary air when the volatilecontent of the pulverized coal increases.

That is, since the fuel nozzle 561 blows the fuel gas obtained by mixingthe pulverized coal with the primary air into the furnace 511 and theprimary air is the transportation air for the pulverized coal, thedistribution of the primary air and the pulverized coal of the fuel gas,that is, the primary air amount is determined by the coal pulverizers531, 532, 533, 534, and 535. Further, the additional air nozzle 539performs oxidization combustion by inputting the combustion air to thecombustion performed by the combustion burners 521, 522, 523, 524, and525 to thereby completely perform the combustion. Here, since theadditional air from the additional air nozzle 539 strengthens thereduction atmosphere in the main combustion zone and reduces the NOxdischarge amount, the additional air amount for each boiler isdetermined.

Meanwhile, the secondary air nozzle 562 is used to blow the air as thesecondary air passing from the air duct 537 to the connection duct 566into the furnace 11, and the air is mainly used as the combustion airwhich is burned while being mixed with the fuel gas blowing from thefuel nozzle 561. The tertiary air nozzle 563 is used to blow the air asthe tertiary air passing from the air duct 537 to the connection duct566 into the furnace 511, and the air is mainly used as the additionalair with respect to the combustion flame as in the additional air nozzle359.

For this reason, the control device 548 changes the opening degree ofthe flowrate adjustment valve 568 so as to adjust the distribution ofthe total air amount of the primary air and the secondary air and thetotal air amount of the tertiary air and the additional air, that is,the distribution of the air amounts of the secondary air and thetertiary air, and hence handle a change in the volatile content of thepulverized coal. Here, when the volatile content of the pulverized coalincreases, the control device 548 decreases the tertiary air amount andincreases the secondary air amount so as to change the distribution ofthe secondary air and the tertiary air.

Here, as illustrated in FIG. 43, when the total air amount of theprimary air and the secondary air increases, the NOx production amountincreases and the unburned combustible content production amountdecreases. That is, in the combustion burners 521, 522, 523, 524, and525, the volatile content of the pulverized coal is mainly burned at theignition portion (the vicinity of the opening portion 551 a of the fuelnozzle 551). Then, when the air amount therein excessively increases,the NOx production amount increases. On the other hand, when the airamount therein is not sufficient, the pulverized coal is not smoothlyburned, and the unburned combustible content production amountincreases. For this reason, in the combustion burners 521, 522, 523,524, and 525, there is a need to set the air amount as the amount inwhich the NOx production amount and the unburned combustible contentproduction amount are suppressed to be low in consideration of thevolatile content of the pulverized coal at the ignition portion.

Furthermore, the volatile content of the pulverized coal is measuredbefore the coal is input to the respective coal pulverizers 531, 532,533, 534, and 535, and the volatile content is stored as data in thecontrol device 548. Further, since the distribution ratio of thesecondary air and the tertiary air with respect to the volatile contentof the pulverized coal becomes different depending on the type of theboiler or the combustion types of the combustion burners 521, 522, 523,524, and 525, the distribution ratio is set in advance by an experiment.For example, a map is prepared, and is stored in the control device 548.

Accordingly, in the combustion burners 521, 522, 523, 524, and 525, thefuel gas blows from the fuel nozzle 561 to the furnace 511, thesecondary air blows from the secondary air nozzle 562 to the furnace,and the tertiary air blows from the tertiary air nozzle 563 to thefurnace. At this time, the fuel gas is ignited and burned by the flamestabilizer 564, and is further burned while being mixed with thesecondary air. At this time, the main combustion zone is formed insidethe furnace 511. Then, since the tertiary air blows from the tertiaryair nozzle 563 to the main combustion zone, the outer peripheral portionof the combustion flame is cooled and the combustion thereof ispromoted. Subsequently, the additional air nozzle 539 blows theadditional air to the furnace 511 so as to perform the combustioncontrol.

That is, in the furnace 511, the combustion gas which is obtained by thecombustion of the fuel gas from the fuel nozzles 561 of the combustionburners 521, 522, 523, 524, and 525 and the secondary air from thesecondary air nozzle 562 becomes less than a theoretical air amount, andthe inside of the furnace is maintained at the reduction atmosphere.Then, the NOx which is produced by the combustion of the pulverized coalis reduced by the tertiary air. Subsequently, the oxidization combustionof the pulverized coal is completed by the additional air, and the NOxproduction amount caused by the combustion of the pulverized coal isreduced.

At this time, the control device 548 obtains the distribution ratio ofthe secondary air and the tertiary air in the combustion burners 521,522, 523, 524, and 525 based on the volatile content of the pulverizedcoal measured in advance and the previously stored distribution ratiomap of the secondary air and the tertiary air with respect to thevolatile content of the pulverized coal, and sets the opening degree ofthe flowrate adjustment valve 568. Then, the control device 548 adjuststhe opening degree of the flowrate adjustment valve 568 based on the setopening degree. Then, in the combustion burners 521, 522, 523, 524, and525, the secondary air amount from the secondary air nozzle 562 and thetertiary air amount from the tertiary air nozzle 563 become optimal forthe volatile content of the pulverized coal, and hence the pulverizedcoal and the volatile content are appropriately burned.

In this way, the boiler of the seventeenth embodiment includes thefurnace 511 which burns the pulverized coal and the air, thesuperheaters 551 and 552 which collect heat by the heat exchange insidethe furnace 511, the fuel nozzle 561 which is able to blow the fuel gasobtained by mixing the pulverized coal with the primary air to thefurnace 511, the secondary air nozzle 562 which is able to blow thesecondary air to the furnace 511, the tertiary air nozzle 563 which isable to blow the tertiary air to the furnace 511, the additional airnozzle 539 which is able to blow the additional air to the upper side ofthe fuel nozzle 561 and the secondary air nozzle 562 in the furnace 511,the flowrate adjustment valve 568 which performs the distribution of thesecondary air amount and the tertiary air amount, and the control device548 which controls the opening degree of the flowrate adjustment valve568 in response to the volatile content of the pulverized coal.

Accordingly, since the control device 548 adjusts the distribution ofthe air amount of the secondary air nozzle 562 and the air amount of thetertiary air nozzle 563 by controlling the opening degree of theflowrate adjustment valve 568 in response to the volatile content of thepulverized coal, the secondary air amount and the tertiary air amountare adjusted in response to the volatile content of the pulverized coal.Accordingly, the volatile content of the pulverized coal may beappropriately burned, and the pulverized coal may be appropriatelyburned. Thus, the production of the NOx or the unburned combustiblecontent may be suppressed, and hence the boiler operation efficiency maybe improved. Further, the pulverized coal and the volatile contentthereof may be appropriately burned while maintaining a predeterminedfuel-air ratio.

Further, in the boiler of the seventeenth embodiment, the control device548 increases the distribution of the secondary air when the volatilecontent of the pulverized coal increases. Since the secondary air is thecombustion air which burns the pulverized coal while being mixed withthe fuel gas, the distribution of the secondary air increases when thevolatile content of the pulverized coal increases, so that thepulverized coal and the volatile content thereof may be appropriatelyburned.

Further, in the method for operating the boiler of the seventeenthembodiment, the distribution of the secondary air and the tertiary airis adjusted in response to the volatile content of the pulverized coalin the pulverized-coal-combustion boiler 510. Accordingly, the volatilecontent of the pulverized coal may be appropriately burned, and thepulverized coal may be appropriately burned. Thus, the production of theNOx or the unburned combustible content may be suppressed, and hence theboiler operation efficiency may be improved.

Furthermore, in the above-described embodiment, the distribution of thesecondary air amount and the tertiary air amount is adjusted and thedistribution of the secondary air increases when the volatile content ofthe pulverized coal increases. However, the invention is not limited tothe configuration. For example, in the coal pulverizers 531, 532, 533,534, and 535, the air amount (the transportation air amount) may beincreased or decreased or the additional air amount may be increased ordecreased.

Further, the boiler of the invention is not limited to the configurationof the pulverized-coal-combustion boiler 510 or the configuration or thenumber of the combustion burners 521, 522, 523, 524, and 525.

Further, in the above-described embodiment, as the combustion device512, four combustion burners 521, 522, 523, 524, and 525 respectivelyprovided in the wall surface of the furnace 511 are disposed as a fivestages in the vertical direction, but the configuration is not limitedthereto. That is, the combustion burner may be disposed at the cornerinstead of the wall surface. Further, the combustion device is notlimited to the turning combustion type, and may be a front combustiontype in which the combustion burner is disposed in one wall surface oran opposed combustion type in which the combustion burners are disposedin two wall surfaces so as to be opposed to each other.

REFERENCE SIGNS LIST

-   -   10 PULVERIZED-COAL-COMBUSTION BOILER    -   11 FURNACE    -   21, 22, 23, 24, 25 COMBUSTION BURNER    -   51, 111 FUEL NOZZLE    -   52, 112 SECONDARY AIR NOZZLE    -   53, 113 TERTIARY AIR NOZZLE    -   54, 71, 81, 91, 114, 121, 131, 161 FLAME STABILIZER    -   55, 75, 95, 101, 115, 135, 141, 151 RECTIFICATION MEMBER    -   210 PULVERIZED-COAL-COMBUSTION BOILER    -   211 FURNACE    -   221, 222, 223, 224, 225 COMBUSTION BURNER    -   251 FUEL NOZZLE    -   252 SECONDARY AIR NOZZLE    -   253 TERTIARY AIR NOZZLE    -   254, 291 FLAME STABILIZER    -   255, 271 GUIDE MEMBER    -   261, 262, 263, 264 FLAME STABILIZING MEMBER    -   261 c, 262 c, 263 c, 264 c NOTCHED SURFACE (GUIDE MEMBER)    -   281, 282, 283, 284 TRIANGULAR PLATE (GUIDE MEMBER)    -   297 DRIVING DEVICE    -   310 TURNING COMBUSTION BOILER    -   311 FURNACE    -   312 BURNER    -   314 ADDITIONAL AIR INPUT UNIT (AA PART)    -   320, 320A SOLID-FUEL-COMBUSTION BURNER    -   321 PULVERIZED COAL BURNER (FUEL BURNER)    -   322 COAL PRIMARY PORT    -   323 COAL SECONDARY PORT    -   324 SPLIT MEMBER    -   324V VERTICAL SPLITTER    -   324H HORIZONTAL SPLITTER    -   330 SECONDARY AIR INPUT PORT    -   340 DAMPER    -   350 TRIANGULAR PLATE (SHIELDING MEMBER)    -   350A TRIANGULAR PYRAMID (SHIELDING MEMBER)    -   410 TURNING COMBUSTION BOILER    -   411 FURNACE    -   412 BURNER    -   414 ADDITIONAL AIR INPUT UNIT (AA PART)    -   420 SOLID-FUEL-COMBUSTION BURNER    -   421 PULVERIZED COAL BURNER (FUEL BURNER)    -   422 COAL PRIMARY PORT    -   423 COAL SECONDARY PORT    -   424 SPLIT MEMBER    -   424 a REMOVING PORTION    -   430 SECONDARY AIR INPUT PORT    -   440 DAMPER    -   510 PULVERIZED-COAL-COMBUSTION BOILER    -   511 FURNACE    -   521, 522, 523, 524, 525 COMBUSTION BURNER    -   537 AIR DUCT    -   539 ADDITIONAL AIR NOZZLE (ADDITIONAL AIR NOZZLE)    -   540 BRANCHED AIR DUCT    -   541, 542, 543, 544, 545, 546, 547, 568 FLOWRATE ADJUSTMENT VALVE        (AIR AMOUNT ADJUSTING DEVICE)    -   548 CONTROL DEVICE    -   551, 552 SUPERHEATER (HEAT EXCHANGER)    -   553, 554 REHEATER (HEAT EXCHANGER)    -   555, 556, 557 ECONOMIZER (HEAT EXCHANGER)    -   561 FUEL NOZZLE    -   562 SECONDARY AIR NOZZLE    -   563 TERTIARY AIR NOZZLE

1. A method for operating a boiler including a furnace that burns solidfuel and air, a heat exchanger that collects heat by a heat exchangeinside the furnace, a fuel nozzle that is arranged to blow a fuel gasobtained by mixing solid fuel with primary air to the furnace, asecondary air nozzle that is arranged to blow secondary air from theoutside of the fuel nozzle into the furnace, and an additional airnozzle that is arranged to blow additional air to the upside of the fuelnozzle and the secondary air nozzle in the furnace, wherein adistribution between a total air amount of the primary air and thesecondary air and an air amount of additional air is adjusted inresponse to a volatile content of the solid fuel.
 2. The method foroperating the boiler according to claim 1, wherein the furnace isprovided with a tertiary air nozzle that is arranged to blow tertiaryair from the outside of the secondary air nozzle, and the control deviceis arranged to control the air amount adjusting device in response tothe volatile content of the solid fuel so as to adjust a distribution ofthe total air amount of the primary air and the secondary air, and thetotal air amount of the tertiary air and the additional air.
 3. Themethod for operating the boiler according to claim 2, wherein thecontrol device is arranged to control the air amount adjusting device sothat the primary air amount and the additional air amount become apredetermined air amount, and to adjust a distribution of the secondaryair and the tertiary air in response to the volatile content of thesolid fuel.
 4. The method for operating the boiler according to claim 2,wherein the control device is arranged to control the air amountadjusting device so that the tertiary air amount and the additional airamount become a predetermined air amount while the primary air and thesecondary air are fixed.
 5. The method for operating the boileraccording to claim 1, wherein the control device is arranged to increasea distribution of the secondary air when the volatile content of thesolid fuel increases.
 6. The method of operating the boiler according toclaim 1, wherein the furnace is provided with a tertiary air nozzle thatis arranged to blow tertiary air from the outside of the secondary airnozzle, and a distribution of the total air amount of the primary airand the secondary air, and the total air amount of the tertiary air andthe additional air is adjusted in response to the volatile content ofthe solid fuel.
 7. The method for operating the boiler according toclaim 1, wherein the distribution of the secondary air is increased whenthe volatile content of the solid fuel is increased.
 8. A boilercomprising: a furnace for burning solid fuel and air; a heat exchangerfor collecting heat by a heat exchange inside the furnace; a fuel nozzlethat is arranged to blow a fuel gas obtained by mixing solid fuel withprimary air into the furnace; a secondary air nozzle that is arranged toblow secondary air from the outside of the fuel nozzle to the furnace;an additional air nozzle that is arranged to blow additional air to theupside of the fuel nozzle and the secondary air nozzle in the furnace;and an air amount adjusting device that is arranged to adjust the amountof the air supplied to the fuel nozzle, the secondary air nozzle, andthe additional air nozzle, and is arranged to control the air amountadjusting device in response to a volatile content of the solid fuel,wherein the control device controls the air amount adjusting device inresponse to the volatile content of the solid fuel so as to adjust adistribution of the total air amount of the primary air and thesecondary air, and an air amount of the additional air.